Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 10,947	$ 10,409
Net unrealized holding gain on securities available for sale	1,179	8,035
Tax effect	(472)	(3,214)
Net unrealized gain on securities available for sale, net of tax	707	4,821
Amortization of net actuarial (gain) loss	(63)	33
Amortization of prior service cost	23	23
Tax effect	16	(23)
Amortization of net actuarial (gain) loss and prior service cost on pension and postretirement plans, net of tax	(24)	33
Other comprehensive income, net of tax	683	4,854
Comprehensive income	$ 11,630	$ 15,263