Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 10,616	$ 10,714	$ 32,058	$ 33,533
Net unrealized holding gain (loss) on securities available for sale	7,855	(1,269)	5,682	17,615
Reclassification adjustments for net gain recognized in income	0	(376)	(249)	(382)
Tax effect	(3,142)	650	(2,171)	(6,893)
Net unrealized gain (loss) on securities available for sale, net of tax	4,713	(995)	3,262	10,340
Amortization of net actuarial loss (gain)	43	(77)	53	(223)
Amortization of prior service cost	23	239	68	149
Tax effect	(26)	(64)	(48)	29
Amortization of net actuarial loss (gain) and prior service cost on pension and postretirement plans, net of tax	40	98	73	(45)
Other comprehensive income (loss), net of tax	4,753	(897)	3,335	10,295
Comprehensive income	$ 15,369	$ 9,817	$ 35,393	$ 43,828