Shareholders' Equity (Income statement reclass) (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (59,913)	$ (50,624)	$ (83,392)
Salaries and Benefits	(216,106)	(213,208)	(203,729)
Net Income	225,913	219,602	184,672
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income	(1,472)	(2,553)	(1,841)
Amortization of Unrealized Gains(Losses) of Investment Securities Transferred from AFS to HTM [Member] | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment Income, Interest	(833)	(2,164)	(1,982)
Provision for Income Taxes	221	569	783
Net Income	(612)	(1,595)	(1,199)
Sale of Investment Securities Available-for-Sale [Member] | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	(49)	0	0
Net Income	103	0	0
Available-for-sale Securities, Gross Realized Gain (Loss)	152	0	0
Amortization of Defined Benefit Pension Items | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	347	310	418
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(1,310)	(1,268)	(1,060)
Net Income	(963)	(958)	(642)
Prior Service Credit | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	288	567	322
Net Actuarial Losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	$ (1,598)	$ (1,835)	$ (1,382)