Federal and State Income Taxes (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets
Allowance for loan and lease losses	$ 50,963	$ 53,555
Other real estate owned	7,685	7,852
Interest rate swap agreements	6,549	3,465
Federal income tax credits	3,543	2,400
Deferred compensation	3,129	2,964
Impairment of equity securities (FHLMC & FNMA)	2,954	2,954
Employee benefits	2,715	2,610
Non-accrued interest	2,008	2,894
Other	2,446	2,713
Total gross deferred tax assets	81,992	81,407
Deferred tax liabilities
Available-for-sale securities	(37,083)	(24,783)
FHLB stock dividends	(10,143)	(10,165)
Depreciation of premises and equipment	(5,437)	(6,169)
Deferred loan costs	(5,316)	(4,954)
Intangibles	(1,832)	(1,566)
Other	(1,787)	(2,689)
Total gross deferred tax liabilities	(61,598)	(50,326)
Net deferred tax asset	$ 20,394	$ 31,081