Accumulated Other Comprehensive Income (Loss) - AOCI Reclass to IS (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
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	$ (58,825)			$ (59,938)			$ (180,088)	$ (177,631)
Provision for Income Tax	(15,767)			(13,765)			(46,704)	(47,130)
Net Income (Loss)	47,903	$ 46,061	$ 46,842	52,801	$ 56,862	$ 54,834	140,806	164,497
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net Income (Loss)	(8,416)			(2,586)			(18,663)	(3,338)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of Unrealized Gains(Losses) of Investment Securities Transferred from AFS to HTM
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Interest Income	(6,787)			(3,037)			(20,500)	(3,100)
Provision for Income Tax	1,800			805			5,434	821
Net Income (Loss)	(4,987)			(2,232)			(15,066)	(2,279)
Reclassification out of Accumulated Other Comprehensive Income | Sale of Investment Securities Available for Sale Member
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Sale of Investment Securities Available-for-Sale	(4,582)			0			(4,582)	0
Provision for Income Tax	1,237			0			1,237	0
Net Income (Loss)	(3,345)			0			(3,345)	0
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	62			61			184	184
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	(177)			(542)			(528)	(1,626)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	(115)			(481)			(344)	(1,442)
Provision for Income Tax	31			127			92	383
Net Income (Loss)	$ (84)			$ (354)			$ (252)	$ (1,059)