Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 39,846	$ 10,368
Securities available for sale:
Unrealized net holding (losses) gains arising during the period, gross	(23,311)	21,339
Tax effect	5,827	(5,335)
Unrealized net holding (losses) gains arising during the period, net	(17,484)	16,004
Reclassification adjustment for net gains in net income, gross	0	(3)
Tax effect	0	1
Reclassification adjustment for net gains in net income, net	0	(2)
Amortization of unrealized net gains for the reclassification of available for sale securities to held to maturity, gross	142	173
Tax effect	(35)	(43)
Amortization of unrealized net gains for the reclassification of available for sale securities to held to maturity, net	107	130
Total securities available for sale, net	(17,377)	16,132
Cash flow hedges:
Unrealized losses on derivatives (cash flow hedges), gross	0	(255)
Tax effect	0	64
Unrealized losses on derivatives (cash flow hedges), net	0	(191)
Reclassification of net unrealized losses on cash flow hedges to interest (income), gross	21	10
Tax effect	(5)	(3)
Reclassification of net unrealized losses on cash flow hedges to interest (income), net	16	7
Total cash flow hedges, net	16	(184)
Pension and other benefits:
Amortization of prior service cost and actuarial losses, gross	326	381
Tax effect	(81)	(95)
Amortization of prior service cost and actuarial losses, net	245	286
Total pension and other benefits, net	245	286
Total other comprehensive (loss) income	(17,116)	16,234
Comprehensive income	$ 22,730	$ 26,602