Mortgage Servicing Rights (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Transfers and Servicing [Abstract]
Outstanding principal balance of loans serviced for others	$ 214,086	$ 211,634
Net gain from sale of loans	496fnlc_NetGainFromSaleOfLoans	1,224fnlc_NetGainFromSaleOfLoans	1,141fnlc_NetGainFromSaleOfLoans
Mortgage servicing rights capitalized	345	743
Amortization of mortgage servicing rights	428	515
Fair value of mortgage servicing rights	2,088us-gaap_ServicingAssetAtFairValueAmount	1,948us-gaap_ServicingAssetAtFairValueAmount
Moving average of weekly prepayment data (in months)	3 months
Anticipated loan prepayment rate of servicing assets (in hundredths)	11.38%
Period used to determine average quarterly discount rate (in years)	10 years
Servicing assets and servicing liabilities at fair value, assumptions used to estimate fair value, discount rate adjustment factor (in hundredths)	4.76%
Summary of mortgage servicing rights [Abstract]
Mortgage servicing rights	6,039fnlc_MortgageServicingRightsGross	7,172fnlc_MortgageServicingRightsGross
Accumulated amortization	(4,949)	(5,988)
Impairment reserve	(4)	(26)
Mortgage Servicing Rights Net	$ 1,086fnlc_MortgageServicingRightsNet	$ 1,158fnlc_MortgageServicingRightsNet

The cumulative amount of amortization for mortgage servicing rights that has been recognized in the income statement.

No definition available.

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- Definition

The average quarterly discount rate period used as assumption in evaluating the carrying value of mortgage servicing rights.

+ References

No definition available.

+ Details

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- Definition

Gross amount, as of the balance sheet date, of mortgage servicing rights.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Net amount, as of the balance sheet date, of mortgage servicing rights.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

The moving average period of weekly prepayment data used as assumption in evaluating the carrying value of mortgage servicing rights.

+ References

No definition available.

+ Details

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- Definition

Net gain from the sale of loans held for sale.

+ References

No definition available.

+ Details

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- Definition

A reserve for the amount of expected decrease in the value of mortgage servicing rights which cannot be physically measured.

+ References

No definition available.

+ Details

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- Definition

Dollar amount of principal outstanding on loans being serviced for others at the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

The amount of rate spread added to the ten-year US Treasury rate to derive the discount rate used in the fair value calculation for the loan servicing portfolio.

+ References

No definition available.

+ Details

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- Definition

The periodic amortization (in proportion to and over the period of estimated net servicing income or loss) of capitalized servicing rights, which contractually entitle the servicer to receive fees and ancillary revenues for performing billing, collection, disbursement and recordkeeping services in connection with a mortgage portfolio. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 4

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122739-111746

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- Definition

The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

+ Details

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- Definition

Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 2

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122596-111746

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- Details

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