Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 10,727	$ 11,808	$ 21,442	$ 22,819
Net unrealized holding (loss) gain on securities available for sale	(5,482)	11,429	(2,173)	18,884
Reclassification adjustments for net gain recognized in income	0	0	(249)	(6)
Tax effect	2,193	(4,517)	971	(7,543)
Net unrealized gain (loss) on securities available for sale, net of tax	(3,289)	6,912	(1,451)	11,335
Amortization of net actuarial loss (gain)	15	(74)	10	(146)
Amortization of prior service cost (credit)	67	(45)	45	(90)
Tax effect	(33)	48	(22)	93
Amortization of net actuarial loss (gain) and prior service cost (credit) on pension and postretirement plans, net of tax	49	(71)	33	(143)
Other comprehensive (loss) income, net of tax	(3,240)	6,841	(1,418)	11,192
Comprehensive income	$ 7,487	$ 18,649	$ 20,024	$ 34,011