Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ (272,799)				$ (272,799)
Investment securities losses (gains), net	$ 0			$ 0			0	$ (8)
HTM investment securities, net, at amortized cost	(2,327)			(2,888)			(6,883)	(7,269)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(13,592)			0			(33,976)	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	4,516			0			9,097	0
Personnel expense	(117,159)			(118,243)			(347,669)	(335,720)
Net other comprehensive loss during period	(47,497)	$ (58,054)	39,211	(72,603)	$ (45,764)	$ (126,708)	(66,340)	(245,074)
Ending Balance	(339,140)						(339,140)
AFS Investment Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(239,273)		(233,192)	(177,726)		(5,266)	(233,192)	(5,266)
Other comprehensive (loss) before reclassifications	(56,924)			(100,092)			(69,512)	(268,413)
Unrealized gains (losses) on AFS securities transferred to HTM securities								(67,604)
Investment securities losses (gains), net								(12)
HTM investment securities, net, at amortized cost	2,327			2,888			6,883	7,269
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	0						0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	0						0
Personnel expense	0			0			0	0
Other expense	0			0			0	0
Income tax benefit	13,928			24,810			15,879	83,906
Net other comprehensive loss during period	(40,669)			(72,394)			(46,751)	(244,854)
Ending Balance	(279,943)	(239,273)		(250,120)	(177,726)		(279,943)	(250,120)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(9,270)		3,360	0		0	3,360	0
Other comprehensive (loss) before reclassifications	0			0			0	0
Unrealized gains (losses) on AFS securities transferred to HTM securities								0
Investment securities losses (gains), net								0
HTM investment securities, net, at amortized cost	0			0			0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(13,592)						(33,976)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	4,516						9,097
Personnel expense	0			0			0	0
Other expense	0			0			0	0
Income tax benefit	2,315			0			5,488	0
Net other comprehensive loss during period	(6,762)			0			(19,391)	0
Ending Balance	(16,032)	(9,270)		0	0		(16,032)	0
Defined Benefit Pension and Postretirement Obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(43,099)		(42,968)	(5,062)		(5,051)	(42,968)	(5,051)
Other comprehensive (loss) before reclassifications	0			0			0	0
Unrealized gains (losses) on AFS securities transferred to HTM securities								0
Investment securities losses (gains), net								0
HTM investment securities, net, at amortized cost	0			0			0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	0						0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	0						0
Personnel expense	(81)			(82)			(244)	(244)
Other expense	(7)			347			15	494
Income tax benefit	23			(474)			31	(470)
Net other comprehensive loss during period	(66)			(209)			(198)	(221)
Ending Balance	(43,166)	(43,099)		(5,272)	(5,062)		(43,166)	(5,272)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(291,642)		(272,799)	(182,788)		(10,317)	(272,799)	(10,317)
Other comprehensive (loss) before reclassifications	(56,924)			(100,092)			(69,512)	(268,413)
Unrealized gains (losses) on AFS securities transferred to HTM securities								(67,604)
Investment securities losses (gains), net								(12)
HTM investment securities, net, at amortized cost	2,327			2,888			6,883	7,269
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(13,592)						(33,976)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	4,516						9,097
Personnel expense	(81)			(82)			(244)	(244)
Other expense	(7)			347			15	494
Income tax benefit	16,266			24,336			21,398	83,436
Net other comprehensive loss during period	(47,497)	(58,054)	$ 39,211	(72,603)	(45,764)	$ (126,708)	(66,340)	(245,074)
Ending Balance	$ (339,140)	$ (291,642)		$ (255,391)	$ (182,788)		$ (339,140)	$ (255,391)