Note 10 - Income Taxes (Detail) - The components of the net deferred tax assets (liabilities): (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax asset:
Postretirement benefits	$ 4,114	$ 3,658
Allowance for loan losses	13,592	13,305
Stock based compensation	2,373	1,942
Depreciation	1,212	1,041
Fair value adjustment on financial assets carried at fair value	3,152	4,024
Other-than-temporary impairment charges	2,700	3,035
Adjustment required to recognize funded status of postretirement pension plans	5,266	5,362
Other	1,991	1,871
Deferred tax asset	34,400	34,238
Deferred tax liability:
Core deposit intangibles	205	411
Valuation differences resulting from acquired assets and liabilities	2,849	2,898
Fair value adjustment on financial liabilities carried at fair value	15,781	15,776
Unrealized gains on securities available for sale	14,697	9,120
Other	1,705	1,993
Deferred tax liability	35,237	30,198
Net deferred tax (liability) asset included in other (liabilities) assets	$ (837)	$ 4,040