Note 10 - Income Taxes (Details) - The Components of the Net Deferred Tax Assets (Liabilities) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax asset:
Postretirement benefits	$ 5,407	$ 4,880
Allowance for loan losses	11,007	13,895
Stock based compensation	2,821	2,322
Depreciation	1,740	1,400
Unrealized loss on securities available for sale		6,612
Fair value adjustment on financial assets carried at fair value		2,470
Derivative financial instruments	1,025
Other-than-temporary impairment charges		1,584
Adjustment required to recognize funded status of postretirement pension plans	4,787	2,218
Other	3,023	2,336
Deferred tax asset	29,810	37,717
Deferred tax liability:
Valuation differences resulting from acquired assets and liabilities	2,764	2,805
Fair value adjustment on financial assets carried at fair value	132
Fair value adjustment on financial liabilities carried at fair value	14,480	14,910
Unrealized gains on securities available for sale	2,588
Other	2,525	1,898
Deferred tax liability	22,489	19,613
Net deferred tax asset included in other assets	$ 7,321	$ 18,104