Regulatory Capital Requirements (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings from prior two years available for dividends	$ 12,738,000
Capital conservation buffer phase in, minimum	0.00%
Capital conservation buffer phase in, maximum	2.50%
Tier 1 capital to risk-weighted assets [Abstract]
Actual	$ 136,637,000	$ 128,970,000
Non Consolidated
Tier 2 capital to risk-weighted asets [Abstract]
Actual	144,255,000	137,818,000
For capital adequacy purpose	74,316,000	68,524,000
To be well-capitalized under prompt corrective action provisions	$ 92,895,000	$ 85,655,000
Risk-weighted assets [Abstract]
Actual (in hundredths)	15.53%	16.09%
For capital adequacy purpose (in hundredths)	8.00%	8.00%
To be well-capitalized under prompt corrective action provisions (in hundredths)	10.00%	10.00%
Actual (in hundredths)	14.45%	14.87%
For capital adequacy purpose (in hundredths)	6.00%	4.00%
To be well-capitalized under prompt corrective action provisions (in hundredths)	8.00%	6.00%
Common equity for capital adequacy purposes (in hundredths)	4.50%
Common equity to be well-capitalized under prompt corrective action provisions (in hundredths)	6.50%
Tier 1 capital to risk-weighted assets [Abstract]
Actual	$ 134,239,000	$ 127,374,000
For capital adequacy purpose	55,737,000	34,262,000
To be well-capitalized under prompt corrective action provisions	74,316,000	51,393,000
Common equity for capital adequacy purpose	41,803,000
Common equity to be well-capitalized under prompt corrective action provisions	60,382,000
Tier 1 capital to average assets [Abstract]
Actual	134,239,000	127,374,000
For capital adequacy purpose	60,885,000	58,086,000
To be well-capitalized under prompt corrective action provisions	$ 76,106,000	$ 72,607,000
Average assets [Abstract]
Actual (in hundredths)	8.82%	8.77%
For capital adequacy purpose (in hundredths)	4.00%	4.00%
To be well-capitalized under prompt corrective action provisions (in hundredths)	5.00%	5.00%
Consolidated
Tier 2 capital to risk-weighted asets [Abstract]
Actual	$ 146,653,000	$ 139,414,000
For capital adequacy purpose	$ 74,357,000	$ 68,532,000
Risk-weighted assets [Abstract]
Actual (in hundredths)	15.78%	16.27%
For capital adequacy purpose (in hundredths)	8.00%	8.00%
Actual (in hundredths)	14.70%	15.06%
For capital adequacy purpose (in hundredths)	6.00%	4.00%
Common equity for capital adequacy purposes (in hundredths)	4.50%
Tier 1 capital to risk-weighted assets [Abstract]
For capital adequacy purpose	$ 55,767,000	$ 34,266,000
Common equity for capital adequacy purpose	41,826,000
Tier 1 capital to average assets [Abstract]
Actual	136,637,000	128,970,000
For capital adequacy purpose	$ 62,022,000	$ 58,066,000
Average assets [Abstract]
Actual (in hundredths)	8.81%	8.88%
For capital adequacy purpose (in hundredths)	4.00%	4.00%

Capital Conservation Buffer Phase in Maximum

No definition available.

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

- Definition

Capital Conservation Buffer Phase in Minimum

+ References

No definition available.

+ Details

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

- Definition

Common Equity Tier 1 Capital Required for Captial Adequacy Purposes

+ References

No definition available.

+ Details

Name:	fnlc_CommonEquityTier1CapitalRequiredforCaptialAdequacyPurposes
Namespace Prefix:	fnlc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Common Equity Tier 1 Capital to Risk-Weighted Assets

+ References

No definition available.

+ Details

Name:	fnlc_CommonEquityTier1CapitaltoRiskWeightedAssets
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Equity Tier One Risk Based Capital Required to be Well Capitalized

+ References

No definition available.

+ Details

Name:	fnlc_CommonEquityTierOneRiskBasedCapitalRequiredtobeWellCapitalized
Namespace Prefix:	fnlc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Common Equity Tier One Risked Based Capital Required to be Well Capitalized to Risk-Weighted Assets

+ References

No definition available.

+ Details

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

- Definition

The amount of retained earnings as of the balance sheet date from the prior two years that can be distributed in the form of dividends.

+ References

No definition available.

+ Details

Name:	fnlc_RetainedEarningsFromPriorTwoYearsAvailableForDividends
Namespace Prefix:	fnlc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of total capital as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

+ Details

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

- Definition

The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958570-112826

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

+ Details

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

- Definition

The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Total Capital divided by risk weighted assets as defined in the regulations.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 Leverage Capital divided by average assets as defined in the regulations.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 Risk Based Capital as defined in the regulations.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The minimum amount of Tier 1 Risk Based Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958570-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 capital divided by risk weighted assets as defined by regulations.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=fnlc_NonConsolidatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fnlc_ConsolidatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: