Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Reclassifications from AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net (gain) on sale of investment securities	$ 0	$ 8	$ 29
Interest expense	(41,755)	(110,656)	(199,456)
Interest income	942,844	1,002,049	1,154,583
Income tax expense	(124,997)	(59,353)	(103,969)
Earnings applicable to common shareholders	398,687	211,474	372,985
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Including Noncontrolling Interest [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net (gain) on sale of investment securities	0	8	29
Available For Sale and Transferred Securities [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	0	6	22
Available For Sale and Transferred Securities [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	0	(2)	(7)
Earnings applicable to common shareholders	0	6	22
Derivative Instruments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	(3,261)	(8,435)	(5,074)
Derivative Instruments | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(4,109)	(7,884)	(5,509)
Interest income	(306)	(3,536)	(1,323)
Income tax expense	1,154	2,985	1,758
Earnings applicable to common shareholders	(3,261)	(8,435)	(5,074)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(4,102)	(3,976)	(5,706)
Defined benefit pension and postretirement benefit plans [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit	1,078	1,036	1,502
Net of tax	$ (3,024)	$ (2,940)	$ (4,204)