Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 232,177	$ 199,759	$ 154,665
Other comprehensive income (loss), net of tax:
Net change in fair value of securities available for sale	295,913	(821,570)	(104,258)
Net change in fair value of cash flow hedges	18,588	(57,520)	(22,454)
Net change in other comprehensive income for defined benefit postretirement plans	339	12,594	15,782
Total other comprehensive income (loss)	314,840	(866,496)	(110,930)
Total comprehensive income (loss)	$ 547,017	$ (666,737)	$ 43,735