Accumulated Other Comprehensive Income (Loss) - AOCI Reclass to IS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	$ (59,924)	$ (56,251)
Provision for Income Tax	(15,606)	(19,025)
Net Income	54,834	59,949
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net Income	(402)	(534)
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	(67)	(125)
Provision for Income Tax	18	32
Net Income	(49)	(93)
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
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	(542)	(662)
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	(480)	(601)
Provision for Income Tax	127	160
Net Income	$ (353)	$ (441)