Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 12,596	$ 10,930	$ 35,783	$ 31,803
Net unrealized holding gain on securities available for sale	938	(125)	5,460	12,475
Reclassification adjustments for net gain recognized in income	0	0	0	(668)
Tax effect	(376)	50	(2,185)	(4,723)
Net unrealized gain on securities available for sale, net of tax	562	(75)	3,275	7,084
Amortization of net actuarial gain	(72)	(8)	(208)	(25)
Amortization of prior service cost	23	22	68	67
Tax effect	20	(6)	56	(17)
Amortization of net actuarial gain and prior service cost on pension and postretirement plans, net of tax	(29)	8	(84)	25
Other comprehensive income, net of tax	533	(67)	3,191	7,109
Comprehensive income	$ 13,129	$ 10,863	$ 38,974	$ 38,912