| **Allowance for Loan Losses TDR's by Class and the Associated Specific Reserves (Details) (USD $)In Thousands, unless otherwise specified** | Jun. 30, 2013loan | Jun. 30, 2012loan |
|---------------------------------------------------------------------------------------------------------------------------------------------|-------------------|-------------------|
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                            |              |              |
| Number of loans                                                                                                                             | 12                | 13                |
| Balance                                                                                                                                     | $ 2,197           | $ 2,487           |
| Specific Reserves                                                                                                                           | 20                | 203               |
| Commercial Real Estate Portfolio Segment [Member]                                                                                           |              |              |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                            |              |              |
| Number of loans                                                                                                                             | 2                 | 1                 |
| Balance                                                                                                                                     | 319               | 269               |
| Specific Reserves                                                                                                                           | 5                 | 111               |
| Commercial Other [Member]                                                                                                                   |              |              |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                            |              |              |
| Number of loans                                                                                                                             | 2                 | 3                 |
| Balance                                                                                                                                     | 370               | 180               |
| Specific Reserves                                                                                                                           | 9                 | 0                 |
| Residential Term [Member]                                                                                                                   |              |              |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                            |              |              |
| Number of loans                                                                                                                             | 7                 | 9                 |
| Balance                                                                                                                                     | 1,085             | 2,038             |
| Specific Reserves                                                                                                                           | 6                 | 92                |
| Home Equity [Member]                                                                                                                        |              |              |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                            |              |              |
| Number of loans                                                                                                                             |              | 0                 |
| Balance                                                                                                                                     |              | 0                 |
| Specific Reserves                                                                                                                           |              | $ 0               |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Specific allowance for loan and lease losses on receivable financings greater 30 days past due that are classified as troubled debt restructurings during the period and that had been placed in TDR status in the previous 12 months.
+ References
No definition available.
+ Details**Name:**fnlc_DaysPastDuePlacedInTDRInPrevious12Months**Namespace Prefix:**fnlc_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The number of financing receivables greater than 30 days past due that have been modified by troubled debt restructurings and that have been placed in the TDR status in the previous 12 months.
+ References
No definition available.
+ Details**Name:**fnlc_FinancingReceivableModificationsNumberOfContractsGreaterThan30DaysPastDuePlaceInTDRInPrevious12Months**Namespace Prefix:**fnlc_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing receivables that are greater than 30 days past due and that had been placed in TDR status in the previous 12 months.
+ References
No definition available.
+ Details**Name:**fnlc_FinancingReceivableRecordedInvestmentGreaterThan30DaysPastDuePlacedInTDRInPrevious12Months**Namespace Prefix:**fnlc_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesAndLoansReceivableLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |