Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 37,775	$ 40,296	$ 76,901	$ 80,142
Securities available for sale:
Unrealized net holding (losses) gains arising during the period, gross	(44,860)	9,408	(135,890)	(13,903)
Tax effect	11,215	(2,352)	33,973	3,475
Unrealized net holding (losses) gains arising during the period, net	(33,645)	7,056	(101,917)	(10,428)
Amortization of unrealized net gains for the reclassification of available for sale securities to held to maturity, gross	131	143	268	285
Tax effect	(32)	(36)	(67)	(71)
Amortization of unrealized net gains for the reclassification of available for sale securities to held to maturity, net	99	107	201	214
Total securities available for sale, net	(33,546)	7,163	(101,716)	(10,214)
Cash flow hedges:
Reclassification of net unrealized losses on cash flow hedges to interest expense, gross	0	0	0	21
Tax effect	0	0	0	(5)
Reclassification of net unrealized losses on cash flow hedges to interest expense, net	0	0	0	16
Total cash flow hedges, net	0	0	0	16
Pension and other benefits:
Amortization of prior service cost and actuarial losses, gross	186	326	372	652
Tax effect	(46)	(82)	(93)	(163)
Amortization of prior service cost and actuarial losses, net	140	244	279	489
Total pension and other benefits, net	140	244	279	489
Total other comprehensive (loss) income	(33,406)	7,407	(101,437)	(9,709)
Comprehensive income (loss)	$ 4,369	$ 47,703	$ (24,536)	$ 70,433