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Note 12 - Stock-based Compensation (Details Textual) - USD ($) $ in Millions |  |  |  |  | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Jun. 06, 2016 | May 28, 2015 | Jan. 02, 2015 | Jun. 01, 2014 | Dec. 31, 2014 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized |  |  |  |  |  | 407,000 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value |  |  |  |  |  | $ 0.1 |  |
First Bank Plans [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross |  |  |  |  |  | 0 | 0 | 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value |  |  |  |  |  | $ 1.2 |  |
Firstbank Corporation [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross |  |  |  | 282,200 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares |  |  |  | 258,400 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number |  |  |  | 23,800 |  |  |  |
First Bank Employees [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period |  |  |  |  |  | 10 years |  |
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares for Maximum Vesting Rights |  |  |  |  |  | 50 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Minimum Number of Shares for Minimum Vesting Rights |  |  |  |  |  | 50 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  |  |  |  | 20.00% |  |
Director [Member] |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Issued for Services | 13,000 | 14,100 | 5,994 |  |  |  |  |
Allocated Share-based Compensation Expense | $ 0.3 | $ 0.3 | $ 0.1 |  |  |  |  |
Stock Issued for Services Share-based Compensation Expense Period | 1 year | 1 year | 150 days |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options |  |  |  |  |  | $ 0.1 |  |
Maximum [Member] | First Bank Employees [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  |  |  |  |  | 5 years |  |
Minimum [Member] | First Bank Employees [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  |  |  |  |  | 1 year |  |
Restricted Stock [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  |  |  |  |  | 3 years | 3 years | 3 years
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost |  |  |  |  | $ 0.2 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options |  |  |  |  |  | $ 4.3 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition |  |  |  |  |  | 3 years |  |
Employee Stock Option [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  |  |  |  |  | 2 years | 2 years | 2 years
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent |  |  |  |  |  | 110.00% | 110.00% | 110.00%
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period |  |  |  |  |  | 7 years | 7 years | 7 years

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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