Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 15,199	$ 12,596	$ 45,412	$ 35,783
Net unrealized holding (loss) gain on securities available for sale	(4,079)	938	(12,908)	5,460
Tax effect	1,069	(376)	3,352	(2,185)
Net unrealized (loss) gain on securities available for sale, net of tax	(3,010)	562	(9,556)	3,275
Amortization of net actuarial gain	(189)	(72)	(367)	(208)
Amortization of prior service cost	(73)	23	(28)	68
Tax effect	68	20	103	56
Amortization of net actuarial gain and prior service cost on pension and postretirement plans, net of tax	(194)	(29)	(292)	(84)
Other comprehensive (loss) income, net of tax	(3,204)	533	(9,848)	3,191
Comprehensive income	$ 11,995	$ 13,129	$ 35,564	$ 38,974