CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 19,740	$ 13,493
Other comprehensive (loss) income:
Net change in unrealized gains on available-for-sale securities, net of tax	(17,509)	18,930
Net change in unrealized gain (loss) on cash flow hedging derivatives, net of tax	5,164	(754)
Net gain on postretirement plans, net of tax	170	133
Other comprehensive (loss) income	(12,175)	18,309
Comprehensive Income	$ 7,565	$ 31,802