Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 10,464	$ 10,727	$ 20,875	$ 21,442
Net unrealized holding gain (loss) on securities available for sale	4,565	(5,482)	12,600	(2,173)
Reclassification adjustments for net gain recognized in income	(668)	0	(668)	(249)
Tax effect	(1,559)	2,193	(4,773)	971
Net unrealized gain (loss) on securities available for sale, net of tax	2,338	(3,289)	7,159	(1,451)
Amortization of net actuarial loss (gain)	(50)	15	(17)	10
Amortization of prior service cost (credit)	22	67	45	45
Tax effect	12	(33)	(11)	(22)
Amortization of net actuarial loss (gain) and prior service cost (credit) on pension and postretirement plans, net of tax	(16)	49	17	33
Other comprehensive income (loss), net of tax	2,322	(3,240)	7,176	(1,418)
Comprehensive income	$ 12,786	$ 7,487	$ 28,051	$ 20,024