Allowance for Loan Losses of Total Loans, Percentage

No definition available.

Name:	fnlc_AllowanceforLoanLossesofTotalLoansPercentage
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Allowance for Loan and Lease Losses, Overlay in Pooled Reserves

+ References

No definition available.

+ Details

Name:	fnlc_AllowanceforLoanandLeaseLossesOverlayinPooledReserves
Namespace Prefix:	fnlc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Allowance for Loan and Lease Losses, Related Loans, Percentage

+ References

No definition available.

+ Details

Name:	fnlc_AllowanceforLoanandLeaseLossesRelatedLoansPercentage
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Allowance for Loan and Lease Losses, Related Loans, Period Increase (Decrease)

+ References

No definition available.

+ Details

Name:	fnlc_AllowanceforLoanandLeaseLossesRelatedLoansPeriodIncreaseDecrease
Namespace Prefix:	fnlc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The high maximum percentage of loan to value for consumer loans based on purchase price of the collateral.

+ References

No definition available.

+ Details

Name:	fnlc_CollateralizedConsumerLoansToIndividualsLoanToValueMaximumRangeHigh
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The low maximum percentage of loan to value for consumer loans based on purchase price of the collateral.

+ References

No definition available.

+ Details

Name:	fnlc_CollateralizedConsumerLoansToIndividualsLoanToValueMaximumRangeLow
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The regulatory maximum allowed ratio of loan portfolio to Company capital for construction and non-owner-occupied commercial real estate.

+ References

No definition available.

+ Details

Name:	fnlc_ConstructionAndNonOwnerOccupiedCommercialRealEstateLoansMaximumLoanPortfolioToCompanyCapital
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The actual ratio of loan amount to Company capital for construction and non-owner-occupied commercial real estate.

+ References

No definition available.

+ Details

Name:	fnlc_ConstructionAndNonOwnerOccupiedCommercialRealEstateLoansPortfolioToCompanyCapital
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The regulatory maximum allowed ratio of loan portfolio to Company capital for construction loans.

+ References

No definition available.

+ Details

Name:	fnlc_ConstructionLoanPortfolioMaximumToCompanyCapital
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The ratio of loan portfolio to Company capital for construction loans .

+ References

No definition available.

+ Details

Name:	fnlc_ConstructionLoansActualLoanPortfolioToCompanyCapital
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Delinquent Period Before Consumer Loans Charged Off

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodBeforeConsumerLoansChargedOff
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum amount of days past due at which residential loans are placed on non-accrual status..

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodBeforeResidentialLoansPlacedOnNonAccrualStatus
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Delinquent Period for Loans Charged Off

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodforLoansChargedOff
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Delinquent Period for Loans Charged Off, Period After Receipt of Notification from Bankruptcy Court

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodforLoansChargedOffPeriodAfterReceiptofNotificationfromBankruptcyCourt
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans and Leases Receivable, Commercial, Number of Loan Classes

+ References

No definition available.

+ Details

Name:	fnlc_LoansandLeasesReceivableCommercialNumberofLoanClasses
Namespace Prefix:	fnlc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Number of Loan Classes

+ References

No definition available.

+ Details

Name:	fnlc_LoansandLeasesReceivableNumberofLoanClasses
Namespace Prefix:	fnlc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Residential, Number of Loan Classes

+ References

No definition available.

+ Details

Name:	fnlc_LoansandLeasesReceivableResidentialNumberofLoanClasses
Namespace Prefix:	fnlc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of loans and commitments subject to review by an independent consulting firm each year.

+ References

No definition available.

+ Details

Name:	fnlc_OutstandingLoansAndCommitmentsSubjectByIndependentConsultingFirm
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Total Reserve Allowance accounted for by Loan Loss Allowances

+ References

No definition available.

+ Details

Name:	fnlc_PercentageofTotalReserveAllowanceaccountedforbyLoanLossAllowances
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The high percentage of loan to value range for residential loans based on current appraisal information.

+ References

No definition available.

+ Details

Name:	fnlc_ResidentialLoansTypicalLoanToValueRangeHigh
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The low percentage of loan to value range for residential loans based on current appraisal information.

+ References

No definition available.

+ Details

Name:	fnlc_ResidentialLoansTypicalLoanToValueRangeLow
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=fnlc_HomeEquityLIneofCreditPortfolioMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fnlc_FinancingReceivableInformationByTypeOfReserveAxis=fnlc_UnallocatedReservesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Allowance for Loan Losses Narrative (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($) loan_class	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of classes in the loan portfolio (loan class) \| loan_class	8
Allowance for loan and lease losses, percent	0.46%	0.45%
Allowance for loan and lease losses, period increase (decrease)	$ 253
Overlay in pooled reserves	1,000
Allowance for loan losses	$ 10,298	$ 9,916	$ 10,198	$ 9,677	$ 9,908	$ 10,344
Allowance for loan losses as a percent of total loans	1.00%	1.00%		1.00%
Number of classes in the commercial loan portfolio (loan class) \| loan_class	3
Residential loans typical loan to value range, maximum	80.00%
Construction loans accrual to company capital	21.90%
Constructions loan portfolio maximum to company capital	100.00%
Construction and non owner occupied commercial real estate	102.90%
Maximum loan portfolio to company capital	300.00%
Outstanding loans and commitments subject by independent consulting firm	50.00%
Number of classes in the residential loan portfolio (loan class) \| loan_class	2
Loan value, lower range	75.00%
Collateralized consumer loans to individuals loan to value maximum, lower range	80.00%
Collateralized consumer loans to individuals loan to value maximum, higher range	90.00%
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 618	$ 566	635	$ 562	580	542
Delinquent period before consumer loans charged off	120 days
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Delinquent period before residential loans placed on non accrual status	90 days
Delinquent Period for Loans Charged Off	180 days
Delinquent Period for Loans Charged Off, Period After Receipt of Notification from Bankruptcy Court	60 days
Home equity line of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 874	893	$ 880	901	$ 918	$ 1,060
Delinquent Period for Loans Charged Off	180 days
Unallocated Reserves
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 1,338	$ 1,873		$ 1,926
Percent of total reserve allowance accounted for by loan loss allowances	13.00%	18.90%