Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 14,071	$ 14,708	$ 38,638	$ 43,933
Net unrealized holding (loss) gain on securities available for sale	(267)	2,418	11,392	14,185
Reclassification adjustments for net gain recognized in income	0	0	(1,155)	0
Tax effect	69	(628)	(2,660)	(3,686)
Net unrealized (loss) gain on securities available for sale, net of tax	(198)	1,790	7,577	10,499
Amortization of net actuarial gain	(222)	(35)	(531)	(103)
Amortization of prior service credit	(49)	(83)	(147)	(250)
Tax effect	70	31	177	92
Amortization of net actuarial gain and prior service credit on pension and postretirement plans, net of tax	(201)	(87)	(501)	(261)
Other comprehensive (loss) income, net of tax	(399)	1,703	7,076	10,238
Comprehensive income	$ 13,672	$ 16,411	$ 45,714	$ 54,171