Unaudited Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 51,516	$ 47,663
Other comprehensive loss, net of tax:
Net change in fair value of securities available for sale	(352,025)	(74,904)
Net change in fair value of cash flow hedges	(3,809)	(5,948)
Net change in other comprehensive income for defined benefit postretirement plans	(124)	426
Total other comprehensive loss	(355,958)	(80,426)
Total comprehensive loss	$ (304,442)	$ (32,763)