| **Loans Loan Portfolio (Details) (USD $)In Thousands, unless otherwise specified** | Jun. 30, 2013 | Dec. 31, 2012 | Jun. 30, 2012 |
|------------------------------------------------------------------------------------|---------------|---------------|---------------|
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | $ 866,071     | $ 869,284     | $ 881,814     |
| Percentage of loans receivable, by type                                            | 100.00%       | 100.00%       | 100.00%       |
| Commercial Real Estate Portfolio Segment [Member]                                  |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 251,799       | 251,335       | 253,193       |
| Percentage of loans receivable, by type                                            | 29.10%        | 28.90%        | 28.70%        |
| Commercial Construction [Member]                                                   |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 18,641        | 22,417        | 33,072        |
| Percentage of loans receivable, by type                                            | 2.20%         | 2.60%         | 3.80%         |
| Commercial Other [Member]                                                          |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 91,393        | 81,183        | 87,833        |
| Percentage of loans receivable, by type                                            | 10.60%        | 9.30%         | 10.00%        |
| Municipal [Member]                                                                 |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 14,885        | 14,704        | 16,089        |
| Percentage of loans receivable, by type                                            | 1.70%         | 1.70%         | 1.80%         |
| Residential Term [Member]                                                          |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 374,522       | 379,447       | 368,876       |
| Percentage of loans receivable, by type                                            | 43.20%        | 43.70%        | 41.80%        |
| Residential Construction [Member]                                                  |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 4,759         | 6,459         | 6,449         |
| Percentage of loans receivable, by type                                            | 0.50%         | 0.70%         | 0.70%         |
| Home Equity [Member]                                                               |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | 95,013        | 99,082        | 100,689       |
| Percentage of loans receivable, by type                                            | 11.00%        | 11.40%        | 11.40%        |
| Consumer Portfolio Segment [Member]                                                |          |          |          |
| **Schedule of Financing Receivables [Line Items]**                                 |          |          |          |
| Loans                                                                              | $ 15,059      | $ 14,657      | $ 15,613      |
| Percentage of loans receivable, by type                                            | 1.70%         | 1.70%         | 1.80%         |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reflects the break down of the gross carrying amount of all categories of loans and leases held in the portfolio, after deducting deferred income, but before deducting the allowance for losses on loans and leases as a percentage of total portfolio.
+ References
No definition available.
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| X                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**fnlc_ScheduleOfFinancingReceivablesLineItems**Namespace Prefix:**fnlc_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes 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 4 -URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5074-111524Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 01-6 -Paragraph 13 -Subparagraph e -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher OTS -Name Federal Regulation (FR) -Number Title 12 -Section 563c.102 -Paragraph 8 -Subparagraph e -Chapter V -Subsection I -LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy.  It will be removed from future versions of this taxonomy.Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-DEP -Paragraph 116 -IssueDate 2006-05-01 -Chapter 8 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.
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