| **Earnings Per Share (Tables)**                                                       | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|---------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Earnings Per Share [Abstract]**                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Basic and diluted earnings per share (EPS)                                            | The following table provides detail for basic earnings per share (EPS) and diluted earnings per share for the years ended December 31, 2012, 2011 and 2010:  Income  Shares  Per-Share   (Numerator)  (Denominator)  Amount For the year ended December 31, 2012      Net income as reported $12,688,000     Less dividends and amortization of premium on preferred stock  723,000     Basic EPS: Income available to common shareholders  11,965,000   9,828,925  $1.22 Effect of dilutive securities: restricted stock      17,606     Diluted EPS: Income available to common shareholders plus assumed conversions $11,965,000   9,846,531  $1.22 For the year ended December 31, 2011            Net income as reported $12,364,000         Less dividends and amortization of premium on preferred stock  1,208,000         Basic EPS: Income available to common shareholders  11,156,000   9,788,610  $1.14 Effect of dilutive securities: incentive stock options and restricted stock      9,619     Diluted EPS: Income available to common shareholders plus assumed conversions $11,156,000   9,798,229  $1.14 For the year ended December 31, 2010            Net income as reported $12,116,000         Less dividends and amortization of premium on preferred stock  1,348,000         Basic EPS: Income available to common shareholders  10,768,000   9,760,760  $1.10 Effect of dilutive securities: incentive stock options and restricted stock      4,726     Diluted EPS: Income available to common shareholders plus assumed conversions $10,768,000   9,765,486  $1.10  |
| Number of options and warrants outstanding and amount above or below the strike price | All earnings per share calculations have been made using the weighted average number of shares outstanding during the period. The dilutive securities are incentive stock options granted to certain key members of Management and warrants granted to the U.S. Treasury under the Capital Purchase Program. The dilutive number of shares has been calculated using the treasury method, assuming that all granted options and warrants were exercisable at the end of each period. The following table presents the number of options and warrants outstanding as of December 31, 2012, 2011 and 2010 and the amount which are above or below the strike price:  Outstanding In-the-Money Out-of-the-MoneyAs of December 31, 2012   Incentive stock options42,000-42,000Warrants issued to U.S. Treasury225,904-225,904Total dilutive securities267,904-267,904As of December 31, 2011   Incentive stock options51,0009,00042,000Warrants issued to U.S. Treasury225,904-225,904Total dilutive securities276,9049,000267,904As of December 31, 2010   Incentive stock options55,50013,50042,000Warrants issued to U.S. Treasury225,904-225,904Total dilutive securities281,40413,500267,904                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of options and warrants issued and outstanding. Disclose the title of issue of securities called for by options and warrants outstanding, the aggregate amount of securities called for by options and warrants outstanding, and the amount above or below the strike price.
+ References
No definition available.
+ Details**Name:**fnlc_ScheduleOfNumberOfOptionsAndWarrantsOutstandingTableTextBlock**Namespace Prefix:**fnlc_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_EarningsPerShareAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of an entity's basic and diluted earnings per share calculations.
+ References
No definition available.
+ Details**Name:**us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |