Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 37,949	$ 27,643	$ 108,503	$ 85,122
Unrealized (losses) gains on securities available for sale:
Unrealized (losses) gains arising during the period	(141,155)	3,673	(432,573)	(16,236)
Tax benefit (expense)	32,437	(844)	99,405	3,731
Postretirement Plans:
Amortization of unrecognized net actuarial loss	44	109	132	485
Tax (expense) benefit	(10)	5	(30)	(112)
Other comprehensive (loss) income	(108,684)	2,943	(333,066)	(12,132)
Comprehensive (loss) income	$ (70,735)	$ 30,586	$ (224,563)	$ 72,990