Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 8,153,000	$ 8,390,000	$ 8,167,000	$ 8,367,000
Other comprehensive income (loss) before reclassification, net of tax	16,000	14,000	109,000	12,000
Amounts reclassified from AOCL, net of tax	(5,000)	(11,000)	(11,000)	(27,000)
Total other comprehensive (loss) income, net of tax	11,000	3,000	98,000	(15,000)
Ending balance	8,095,000	8,397,000	8,095,000	8,397,000
Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(553,000)	(617,000)	(640,000)	(599,000)
Total other comprehensive (loss) income, net of tax	11,000	3,000	98,000	(15,000)
Ending balance	(542,000)	(614,000)	(542,000)	(614,000)
Debt Securities AFS
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(560,000)	(651,000)	(653,000)	(581,000)
Other comprehensive income (loss) before reclassification, net of tax	16,000	(23,000)	109,000	(93,000)
Amounts reclassified from AOCL, net of tax	0	0	0	0
Total other comprehensive (loss) income, net of tax	16,000	(23,000)	109,000	(93,000)
Ending balance	(544,000)	(674,000)	(544,000)	(674,000)
Other comprehensive income (loss) before reclassifications, tax	(6,000)	8,000	(38,000)	31,000
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	40,000	61,000	47,000	10,000
Other comprehensive income (loss) before reclassification, net of tax	0	39,000	0	107,000
Amounts reclassified from AOCL, net of tax	(5,000)	(12,000)	(12,000)	(29,000)
Total other comprehensive (loss) income, net of tax	(5,000)	27,000	(12,000)	78,000
Ending balance	35,000	88,000	35,000	88,000
Other comprehensive income (loss) before reclassifications, tax	0	(13,000)	0	(36,000)
Pension and Post-retirement Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(33,000)	(27,000)	(34,000)	(28,000)
Other comprehensive income (loss) before reclassification, net of tax	0	(2,000)	0	(2,000)
Amounts reclassified from AOCL, net of tax	0	1,000	1,000	2,000
Total other comprehensive (loss) income, net of tax	0	(1,000)	1,000	0
Ending balance	$ (33,000)	$ (28,000)	$ (33,000)	$ (28,000)