Accumulated Other Comprehensive Income (Loss) (AOCI Reclass to IS) (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Tax Benefit (Expense)	$ (7,461)	$ (13,660)
Net Income	34,742	58,799
Salaries and Benefits	(54,463)	(56,586)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net Income	(366)	(584)
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	(65)	(396)
Tax Benefit (Expense)	17	105
Net Income	(48)	(291)
Reclassification out of Accumulated Other Comprehensive Income | Sale of Investment Securities Available-for-Sale
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Tax Benefit (Expense)	(21)	17
Net Income	56	(47)
Sale of Investment Securities Available-for-Sale	77	(64)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of Defined Benefit Pension Items
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Tax Benefit (Expense)	135	88
Net Income	(374)	(246)
Salaries and Benefits	(509)	(334)
Reclassification out of Accumulated Other Comprehensive Income | Prior Service Credit
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	61	72
Reclassification out of Accumulated Other Comprehensive Income | Net Actuarial Losses
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	$ (570)	$ (406)