Note 2 - Business Combination (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended			0 Months Ended		4 Months Ended		3 Months Ended			0 Months Ended	1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Restricted Stock [Member] Firstbank Corporation [Member]	Sep. 30, 2014 Employee Stock Option [Member] Firstbank Corporation [Member]	Jun. 01, 2014 Employee Stock Option [Member] Firstbank Corporation [Member]	Jun. 01, 2014 Acquired Trusts [Member] Firstbank Corporation [Member] London Interbank Offered Rate (LIBOR) [Member] Minimum [Member]	Jun. 01, 2014 Acquired Trusts [Member] Firstbank Corporation [Member] London Interbank Offered Rate (LIBOR) [Member] Maximum [Member]	Sep. 30, 2014 Servicing Contracts [Member] Firstbank Corporation [Member]	Jun. 01, 2014 Servicing Contracts [Member] Firstbank Corporation [Member]	Sep. 30, 2014 Firstbank Corporation [Member] Minimum [Member]	Sep. 30, 2014 Firstbank Corporation [Member] Maximum [Member]	Jun. 01, 2014 Firstbank Corporation [Member] Maximum [Member]	Jun. 01, 2014 Firstbank Corporation [Member]	Jun. 30, 2014 Firstbank Corporation [Member]	Sep. 30, 2014 Firstbank Corporation [Member]	Sep. 30, 2013 Firstbank Corporation [Member]	Sep. 30, 2014 Firstbank Corporation [Member]	Sep. 30, 2014 Firstbank Corporation [Member]	Jun. 01, 2014 Firstbank Corporation [Member]	Jun. 01, 2014 Firstbank Corporation [Member] Estimate of Fair Value Measurement [Member]
Note 2 - Business Combination (Details) [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets																						$ 1,451,483,000
Business Combination, Branches Acquired																						46
Business Acquisition, Conversion of Stock Per Share (in Shares)																1
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares)																8,087,272	8,087,272
Goodwill	50,870,000		50,870,000		0																	50,870,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles												7,400,000
Amortization											200,000									600,000
Business Combination, Acquisition Related Costs	1,250,000	719,000	5,081,000	779,000														1,300,000	700,000		5,100,000
Business Combination, Acquired Receivables and Certain Loans, Estimated Uncollectible Cash Flows																						10,400,000
Business Combination, Acquired Receivables and Certain Loans, Pre-acquisition Charge-offs																						2,800,000
Business Combination, Acquired Receivables and Certain Loans, Estimated Uncollectible Interest																						3,900,000
Business Combination, Acquired Receivables, Gross Contractual Amount																						926,400,000
Business Combination, Acquired Receivables, Unaccredted Discount																						8,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt																						36,100,000	21,100,000
Business Combination, Debt Assumed, Number of Trusts																						4
Debt Instrument, Basis Spread on Variable Rate									1.27%	1.99%
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost						200,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)															282,200
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number (in Shares)								258,400
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number (in Shares)							23,800
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period													6 months	18 months
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options														100,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value																		2,000,000		2,000,000	2,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value																		$ 2,000,000		$ 2,000,000	$ 2,000,000