XML 37 R61.htm IDEA: XBRL DOCUMENT v2.4.1.9
Loans (Details) (USD $)
12 Months Ended
Dec. 31, 2014
loan
Dec. 31, 2013
loan
Dec. 31, 2012
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio $ 917,564,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome $ 876,367,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome $ 869,284,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Percentage of loan portfolio (in hundredths) 100.00%fnlc_PercentageOfLoansReceivableByType 100.00%fnlc_PercentageOfLoansReceivableByType  
Loans Receivable to Related Party [Roll Forward]      
Balance at beginning of year 14,884,000fnlc_RelatedPartyLoanReceivableAggregatedOver60000Dollars 14,917,000fnlc_RelatedPartyLoanReceivableAggregatedOver60000Dollars  
New loans 8,932,000fnlc_LoansandLeasesReceivablesRelatedPartiesAdditionsAggregatedOver60000Dollars 909,000fnlc_LoansandLeasesReceivablesRelatedPartiesAdditionsAggregatedOver60000Dollars  
Repayments (8,960,000)fnlc_LoansandLeasesReceivablesRelatedPartiesCollectionsAggregatedOver60000Dollars (942,000)fnlc_LoansandLeasesReceivablesRelatedPartiesCollectionsAggregatedOver60000Dollars  
Balance at end of year 14,856,000fnlc_RelatedPartyLoanReceivableAggregatedOver60000Dollars 14,884,000fnlc_RelatedPartyLoanReceivableAggregatedOver60000Dollars 14,917,000fnlc_RelatedPartyLoanReceivableAggregatedOver60000Dollars
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 2,142,000fnlc_LoansReceivable3059DaysPastDue 1,588,000fnlc_LoansReceivable3059DaysPastDue  
Loans Receivable 60 89 Days Past Due 1,356,000fnlc_LoansReceivable6089DaysPastDue 2,471,000fnlc_LoansReceivable6089DaysPastDue  
90 Plus Days Past Due 8,365,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue 11,933,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue  
All Past Due 11,863,000us-gaap_FinancingReceivableRecordedInvestmentPastDue 15,992,000us-gaap_FinancingReceivableRecordedInvestmentPastDue  
Current 905,701,000us-gaap_FinancingReceivableRecordedInvestmentCurrent 860,375,000us-gaap_FinancingReceivableRecordedInvestmentCurrent  
Amount of loan portfolio 917,564,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome 876,367,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome 869,284,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
90 Plus Days And Accruing 181,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing 1,043,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing  
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 10,510,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus 16,318,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus  
Average investment in impaired loans 38,404,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 45,722,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 45,019,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Interest income recognized on impaired loans, all on cash basis 1,465,000us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod 1,750,000us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod 1,039,000us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod
Balance of impaired loans 35,862,000us-gaap_ImpairedFinancingReceivableRecordedInvestment 42,351,000us-gaap_ImpairedFinancingReceivableRecordedInvestment 45,744,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
Less portion for which no allowance for loan losses is allocated (26,313,000)fnlc_ImpairedFinancingReceivableWithNoAllowance (32,417,000)fnlc_ImpairedFinancingReceivableWithNoAllowance  
Portion of impaired loan balance for which an allowance for loan losses is allocated 9,549,000fnlc_ImpairedFinancingReceivableWithAllowance 9,934,000fnlc_ImpairedFinancingReceivableWithAllowance  
Portion of allowance for loan losses allocated to the impaired loan balance 826,000fnlc_FinancingReceivableModificationsPreModificationRecordedInvestmentDuringPeriod 3,604,000fnlc_FinancingReceivableModificationsPreModificationRecordedInvestmentDuringPeriod  
Recorded Investment 35,862,000us-gaap_ImpairedFinancingReceivableRecordedInvestment 42,351,000us-gaap_ImpairedFinancingReceivableRecordedInvestment 45,744,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
Unpaid Principal Balance 39,026,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance 46,408,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance 49,542,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Related Allowance 1,803,000us-gaap_ImpairedFinancingReceivableRelatedAllowance 2,461,000us-gaap_ImpairedFinancingReceivableRelatedAllowance 3,539,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
Average Recorded Investment 38,404,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 45,722,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 45,019,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Recognized Interest Income 1,465,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod 1,750,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod 1,039,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Troubled Debt Restructured, Number of Loans 94us-gaap_FinancingReceivableModificationsNumberOfContracts2 99us-gaap_FinancingReceivableModificationsNumberOfContracts2  
Troubled Debt Restructured, Balance 27,214,000us-gaap_FinancingReceivableModificationsRecordedInvestment 29,098,000us-gaap_FinancingReceivableModificationsRecordedInvestment  
Troubled Debt Restructured, Specific Reserves 868,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod 1,017,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod  
Troubled Debt Restructured (Greater than 30 days), Number of Loans 12fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months 16fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months  
Troubled Debt Restructured (Greater than 30 days), Balance 1,549,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months 3,261,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months  
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 177,000fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod 37,000fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod  
Financing Receivable, Number of Loans 6fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod 10fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod  
Financing Receivable, Pre-Modification Outstanding Recorded Investment 929,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 3,610,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2  
Financing Receivable, Post-Modification Outstanding Recorded Investment 826,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 3,604,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2  
Financing Receivable, Specific Reserves 12,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod 31,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod  
Net deferred loan costs included in loan balances 2,729,000us-gaap_LoansAndLeasesReceivableDeferredIncome 2,086,000us-gaap_LoansAndLeasesReceivableDeferredIncome  
Loans used to collateralize borrowings from the Federal Home Loan Bank of Boston 266,716,000us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1 266,740,000us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1  
Commercial, construction and home equity loans used to collateralize unused line of credit at the Federal Reserve Bank of Boston 240,943,000us-gaap_LoansPledgedAsCollateral 189,728,000us-gaap_LoansPledgedAsCollateral  
Interest income which would have been recognized on these loans, if interest had been accrued 551,000us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans 917,000us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans 1,158,000us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans
Due from Related Parties 29,883,000us-gaap_DueFromRelatedParties 28,821,000us-gaap_DueFromRelatedParties  
Balance of loans classified as TDRs, greater than 30 days past due 1,549,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDue 3,261,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDue  
Financing Receivable, Modifications, Subsequent Default, Number of Contracts 2us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 6us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1  
Financing Receivable, Loans Classified as Troubled Debt Restructurings That Had Been Placed on TDR Status in Previous 12 Months 238,000fnlc_FinancingReceivableLoansClassifiedasTroubledDebtRestructuringsThatHadBeenPlacedonTDRStatusinPrevious12Months 810,000fnlc_FinancingReceivableLoansClassifiedasTroubledDebtRestructuringsThatHadBeenPlacedonTDRStatusinPrevious12Months  
Loans classified as TDRs that are involved in bankruptcy 1,215,000fnlc_FinancingReceivableLoansClassifiedAsTroubledDebtRestructuringsThatAreInvolvedInBankruptcy    
Number of loans classified as TDRs that were on non-accrual status 16fnlc_FinancingReceivableNumberOfLoansClassifiedAsTroubledDebtRestructuringsThatWereOnNonAccrualStatus    
Loans classified as TDRs that were on non-accrual status 2,496,000fnlc_FinancingReceivableLoansClassifiedAsTroubledDebtRestructuringsThatWereOnNonAccrualStatus    
Number of loans classified as TDRs that are involved in foreclosure 5fnlc_NumberOfLoansClassifiedAsTroubledDebtRestructuringsThatAreInvolvedInForeclosure    
Loans classified as TDRs that are involved in foreclosure 611,000fnlc_LoansClassifiedAsTroubledDebtRestructuringsThatAreInvolvedInForeclosure    
With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 11,478,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
14,181,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
18,182,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 9,549,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
9,934,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
17,462,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 9,549,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
9,934,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
17,462,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 9,949,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
10,289,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
18,239,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 1,803,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
2,461,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,539,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 11,478,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
14,181,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
18,182,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 387,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
390,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
571,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 26,926,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
31,541,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
26,837,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 26,313,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
32,417,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
28,282,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 26,313,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
32,417,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
28,282,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 29,077,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
36,119,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
31,303,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 26,926,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
31,541,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
26,837,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 1,078,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,360,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
468,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Commercial Real Estate Other Receivable      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 15us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
20us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
 
Troubled Debt Restructured, Balance 2,007,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
2,734,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
 
Troubled Debt Restructured, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
100,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 1fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
2fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 2,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
355,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
 
Commercial Real Estate      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 19us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
20us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
 
Troubled Debt Restructured, Balance 12,282,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
13,018,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
 
Troubled Debt Restructured, Specific Reserves 267,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
433,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 1fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
2fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 321,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
990,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 120,000fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateMember
 
Commercial Construction      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 1us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Troubled Debt Restructured, Balance 1,172,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,284,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Troubled Debt Restructured, Specific Reserves 207,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
274,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Municipal      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 0us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_MunicipalMember
 
Troubled Debt Restructured, Balance 0us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_MunicipalMember
 
Troubled Debt Restructured, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_MunicipalMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_MunicipalMember
 
Residential Term      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 54us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
53us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
 
Troubled Debt Restructured, Balance 10,932,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
11,220,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
 
Troubled Debt Restructured, Specific Reserves 373,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
210,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 8fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
10fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 1,000,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
1,688,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 36,000fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
37,000fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialTermMember
 
Residential Construction      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 0us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
 
Troubled Debt Restructured, Balance 0us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
 
Troubled Debt Restructured, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_ResidentialConstructionMember
 
Home equity line of credit      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 5us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
5us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
 
Troubled Debt Restructured, Balance 821,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
842,000us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
 
Troubled Debt Restructured, Specific Reserves 21,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 2fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
2fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 226,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
228,000fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 21,000fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_HomeEquityMember
 
Consumer      
Nonaccrual Loans [Abstract]      
Troubled Debt Restructured, Number of Loans 0us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableModificationsNumberOfContracts2
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
 
Troubled Debt Restructured, Balance 0us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableModificationsRecordedInvestment
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
 
Troubled Debt Restructured, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceDuringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
 
Troubled Debt Restructured (Greater than 30 days), Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= us-gaap_ConsumerLoanMember
 
Commercial Other      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 104,531,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
95,289,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
81,183,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Percentage of loan portfolio (in hundredths) 11.40%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
10.90%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 3,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
544,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Loans Receivable 60 89 Days Past Due 0fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
128,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
90 Plus Days Past Due 857,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
2,797,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
All Past Due 860,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
3,469,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Current 103,671,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
91,820,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Amount of loan portfolio 104,531,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
95,289,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
81,183,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
90 Plus Days And Accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 935,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
4,370,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Average investment in impaired loans 4,956,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
5,898,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
4,851,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Balance of impaired loans 2,942,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
6,698,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
5,861,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Recorded Investment 2,942,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
6,698,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
5,861,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Unpaid Principal Balance 3,745,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
8,441,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
6,471,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Related Allowance 129,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
841,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
652,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Average Recorded Investment 4,956,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
5,898,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
4,851,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Recognized Interest Income 169,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
350,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
91,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
Financing Receivable, Number of Loans   2fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment   491,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment   491,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Financing Receivable, Specific Reserves   0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
 
Commercial Other | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 1,103,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,633,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,974,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 326,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,081,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,124,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 326,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,081,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,124,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 338,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,132,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,126,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 129,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
841,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
652,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 1,103,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,633,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,974,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 13,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
28,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
38,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Commercial Other | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 3,853,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
4,265,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
2,877,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 2,616,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
5,617,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
4,737,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 2,616,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
5,617,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
4,737,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 3,407,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
7,309,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
5,345,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 3,853,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
4,265,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
2,877,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 156,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
322,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
53,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialOtherMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Commercial Real Estate Other Receivable      
Nonaccrual Loans [Abstract]      
Financing Receivable, Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
   
Financing Receivable, Pre-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
   
Financing Receivable, Post-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
   
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
   
Consumer Portfolio Segment      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 19,653,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
15,066,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
14,657,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Loans, aging disclosure [Abstract]      
Amount of loan portfolio 19,653,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
15,066,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
14,657,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Nonaccrual Loans [Abstract]      
Financing Receivable, Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Commercial Construction      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 30,932,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
20,382,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
22,417,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
Loans, aging disclosure [Abstract]      
Amount of loan portfolio 30,932,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
20,382,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
22,417,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
Nonaccrual Loans [Abstract]      
Financing Receivable, Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
 
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_CommercialConstructionMember
 
Commercial Real Estate Portfolio Segment      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 242,311,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
245,943,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
251,335,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Loans, aging disclosure [Abstract]      
Amount of loan portfolio 242,311,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
245,943,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
251,335,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Nonaccrual Loans [Abstract]      
Financing Receivable, Number of Loans 2fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
2fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 302,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
1,883,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 300,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
1,883,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
 
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
 
Commercial Real Estate      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 242,311,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
245,943,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Percentage of loan portfolio (in hundredths) 26.40%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
28.20%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 24,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
82,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Loans Receivable 60 89 Days Past Due 75,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
259,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
90 Plus Days Past Due 761,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
745,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
All Past Due 860,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
1,086,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Current 241,451,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
244,857,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Amount of loan portfolio 242,311,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
245,943,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
90 Plus Days And Accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 2,088,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
2,457,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
 
Average investment in impaired loans 14,120,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
16,773,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
14,716,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Balance of impaired loans 13,304,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
14,935,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
15,774,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Recorded Investment 13,304,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
14,935,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
15,774,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Unpaid Principal Balance 14,212,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
15,683,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
16,981,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Related Allowance 346,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
890,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
1,523,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Average Recorded Investment 14,120,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
16,773,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
14,716,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Recognized Interest Income 550,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
645,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
410,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Commercial Real Estate | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 3,040,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
5,673,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,614,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 1,617,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,122,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
6,388,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 1,617,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,122,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
6,388,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 1,789,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,264,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
7,018,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 346,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
890,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,523,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 3,040,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
5,673,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,614,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 62,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
150,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
211,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Commercial Real Estate | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 11,080,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
11,100,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
10,102,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 11,687,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
11,813,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
9,386,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 11,687,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
11,813,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
9,386,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 12,423,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
12,419,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
9,963,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 11,080,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
11,100,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
10,102,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 488,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
495,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
199,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Commercial Construction      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 30,932,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
20,382,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Percentage of loan portfolio (in hundredths) 3.40%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
2.30%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 0fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Loans Receivable 60 89 Days Past Due 41,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
90 Plus Days Past Due 208,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
All Past Due 249,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Current 30,683,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
20,382,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Amount of loan portfolio 30,932,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
20,382,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
90 Plus Days And Accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 208,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
 
Average investment in impaired loans 1,309,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,997,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
4,349,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Balance of impaired loans 1,380,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,284,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
3,354,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Recorded Investment 1,380,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,284,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
3,354,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Unpaid Principal Balance 1,380,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,284,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
3,368,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Related Allowance 413,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
272,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
969,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Average Recorded Investment 1,309,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,997,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
4,349,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Recognized Interest Income 56,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
48,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
85,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Commercial Construction | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 1,279,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,795,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,816,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 1,380,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,284,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,253,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 1,380,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,284,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,253,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 1,380,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,284,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
3,253,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 413,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
272,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
969,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 1,279,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,795,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
1,816,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 56,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
48,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
85,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Commercial Construction | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 30,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
202,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
2,533,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
101,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
101,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
115,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 30,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
202,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
2,533,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Municipal      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 20,424,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
19,117,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
14,704,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Percentage of loan portfolio (in hundredths) 2.20%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
2.20%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 0fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Loans Receivable 60 89 Days Past Due 0fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
90 Plus Days Past Due 0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
All Past Due 0us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Current 20,424,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
19,117,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Amount of loan portfolio 20,424,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
19,117,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
14,704,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
90 Plus Days And Accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
Troubled Debt Restructured (Greater than 30 days), Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Troubled Debt Restructured (Greater than 30 days), Balance 0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Troubled Debt Restructured (Greater than 30 days), Specific Reserves 0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_FinancingReceivableRecordedInvestmentGreaterthan30DaysPastDuePlacedinTDRinPrevious12monthsSpecificAllowanceduringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Financing Receivable, Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
 
Municipal | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Municipal | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_MunicipalMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Residential Term      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 384,032,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
377,218,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
379,447,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Percentage of loan portfolio (in hundredths) 41.90%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
43.00%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 856,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
229,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Loans Receivable 60 89 Days Past Due 468,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
1,913,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
90 Plus Days Past Due 5,679,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
7,002,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
All Past Due 7,003,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
9,144,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Current 377,029,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
368,074,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Amount of loan portfolio 384,032,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
377,218,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
379,447,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
90 Plus Days And Accruing 101,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
596,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 6,421,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
8,484,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Average investment in impaired loans 16,243,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
19,378,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
18,867,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Balance of impaired loans 16,123,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
17,786,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
19,444,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Recorded Investment 16,123,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
17,786,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
19,444,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Unpaid Principal Balance 17,337,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
19,116,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
21,282,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Related Allowance 519,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
404,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
395,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Average Recorded Investment 16,243,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
19,378,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
18,867,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Recognized Interest Income 641,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
673,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
426,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
Financing Receivable, Number of Loans 4fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
5fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 627,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
1,032,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 526,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
1,029,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Financing Receivable, Specific Reserves 12,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
31,000fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
 
Residential Term | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 5,738,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,982,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
9,066,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 5,303,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,354,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
6,697,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 5,303,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,354,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
6,697,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 5,513,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,516,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
6,842,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 519,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
404,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
395,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 5,738,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
4,982,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
9,066,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 239,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
162,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
237,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Residential Term | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 10,505,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
14,396,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
9,801,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 10,820,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
13,432,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
12,747,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 10,820,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
13,432,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
12,747,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 11,824,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
14,600,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
14,440,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 10,505,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
14,396,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
9,801,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 402,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
511,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
189,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialTermMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Residential Construction      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 12,160,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
11,803,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
6,459,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Percentage of loan portfolio (in hundredths) 1.30%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
1.30%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 0fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
47,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Loans Receivable 60 89 Days Past Due 0fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
90 Plus Days Past Due 0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
All Past Due 0us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
47,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Current 12,160,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
11,756,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Amount of loan portfolio 12,160,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
11,803,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
6,459,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
90 Plus Days And Accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
821,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
821,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
Financing Receivable, Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
 
Residential Construction | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
261,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
261,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Residential Construction | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
560,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
560,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= fnlc_ResidentialConstructionMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Home equity line of credit      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 103,521,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
91,549,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
99,082,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Percentage of loan portfolio (in hundredths) 11.30%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
10.40%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 622,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
573,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Loans Receivable 60 89 Days Past Due 720,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
145,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
90 Plus Days Past Due 780,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,001,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
All Past Due 2,122,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,719,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Current 101,399,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
89,830,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Amount of loan portfolio 103,521,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
91,549,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
99,082,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
90 Plus Days And Accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
59,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 832,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,007,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Average investment in impaired loans 1,765,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,676,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,403,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Balance of impaired loans 2,087,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,648,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,311,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Recorded Investment 2,087,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,648,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,311,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Unpaid Principal Balance 2,324,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,884,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,440,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Related Allowance 396,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
54,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Average Recorded Investment 1,765,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,676,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1,403,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Recognized Interest Income 46,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
34,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
27,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
Financing Receivable, Number of Loans 0fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
1fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Financing Receivable, Pre-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
204,000us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Financing Receivable, Post-Modification Outstanding Recorded Investment 0us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
201,000us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Financing Receivable, Specific Reserves 0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
0fnlc_TroubledDebtRestructuringLoansAndLeasesReceivableSpecificAllowanceCurrentPeriod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Home equity line of credit | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 318,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
98,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
442,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 923,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
93,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 923,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
93,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 929,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
93,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 396,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
54,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 318,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
98,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
442,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 17,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
2,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Home equity line of credit | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 1,447,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,578,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
961,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 1,164,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,555,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,311,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 1,164,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,555,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,311,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 1,395,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,791,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,440,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 1,447,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
1,578,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
961,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income 29,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
32,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
27,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Consumer      
Composition of Loan Portfolio [Abstract]      
Amount of loan portfolio 19,653,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
15,066,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Percentage of loan portfolio (in hundredths) 2.10%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
1.70%fnlc_PercentageOfLoansReceivableByType
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Loans, aging disclosure [Abstract]      
Loans Receivable 30 59 Days Past Due 637,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
113,000fnlc_LoansReceivable3059DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Loans Receivable 60 89 Days Past Due 52,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
26,000fnlc_LoansReceivable6089DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
90 Plus Days Past Due 80,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
388,000us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
All Past Due 769,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
527,000us-gaap_FinancingReceivableRecordedInvestmentPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Current 18,884,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
14,539,000us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Amount of loan portfolio 19,653,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
15,066,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
90 Plus Days And Accruing 80,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
388,000us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Nonaccrual Loans [Abstract]      
Nonaccrual Loans Receivable 26,000us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
 
Average investment in impaired loans 11,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
12,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Balance of impaired loans 26,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Recorded Investment 26,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Unpaid Principal Balance 28,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Average Recorded Investment 11,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
12,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Recognized Interest Income 3,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Consumer | With an Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
9,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Balance of impaired loans 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recorded Investment 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Average Recorded Investment 0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
9,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Recognized Interest Income 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithAllowanceRecordedMember
Consumer | With No Related Allowance Recorded      
Nonaccrual Loans [Abstract]      
Average investment in impaired loans 11,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
3,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Balance of impaired loans 26,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recorded Investment 26,000us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Unpaid Principal Balance 28,000us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Average Recorded Investment 11,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
0us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
3,000us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Recognized Interest Income $ 3,000us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
$ 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
$ 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_FinancingReceivableTroubledDebtRestructuringAxis
= fnlc_WithNoRelatedAllowanceRecordedMember
Loans Receivable in Bankruptcy      
Nonaccrual Loans [Abstract]      
Financing Receivable, Number of Loans 9fnlc_FinancingReceivableModificationsNumberOfContractsDuringPeriod
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember