Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net Income	$ 63,206	$ 72,097	$ 220,122	$ 220,017
Other Comprehensive Income (Loss), net of tax:
Net unrealized holding gains (losses)	68,560	(105,050)	37,696	(103,628)
Reclassification adjustment for securities net change realized in net income	1	0	15,689	14
Amortization of net unrealized gains on AFS securities transferred to HTM	1,422	1,494	4,212	4,473
Net unrealized gains (losses) on AFS investment securities	69,983	(103,556)	57,597	(99,141)
Net unrealized holding (losses) gains	(6,624)	3,651	(71)	(8,755)
Reclassification adjustment for net change realized in net income	3,979	6,420	11,769	20,573
Net unrealized (losses) gains on interest rate derivatives used in cash flow hedges	(2,645)	10,071	11,698	11,818
Amortization of net unrecognized pension and postretirement items	(106)	15	(317)	43
Other Comprehensive Income (Loss), net of tax	67,232	(93,470)	68,978	(87,280)
Total Comprehensive Income	$ 130,438	$ (21,373)	$ 289,100	$ 132,737