Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Consolidated Statements of Comprehensive Income (Loss) (Unaudited) [Abstract]
Net income	$ 9,763	$ 9,066	$ 18,931	$ 17,975
Net unrealized holding gain (loss) on securities available for sale	(26,315)	2,571	(29,254)	7,451
Reclassification adjustments for net gain recognized in income	(1,432)	(55)	(1,434)	(732)
Tax effect	11,064	(1,003)	12,237	(2,679)
Net unrealized gain (loss) on securities available for sale	(16,683)	1,513	(18,451)	4,040
Amortization of net actuarial loss	101	97	233	194
Amortization of prior service credit	(65)	(65)	(131)	(131)
Tax effect	(15)	(13)	(40)	(25)
Amortization of net actuarial loss and prior service credit on pension and postretirement plans, net of tax	21	19	62	38
Other comprehensive income (loss), net of tax	(16,662)	1,532	(18,389)	4,078
Comprehensive income (loss)	$ (6,899)	$ 10,598	$ 542	$ 22,053