Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (53,935)	$ 80,069
Net change in unrealized gain or loss	(390,904)	(145,490)
Reclassification of net income or loss realized and included in earnings	(3,838)	286
Amortization of unrealized net gain or loss on securities transferred to HTM	261	(56)
Income tax expense (benefit)	(89,140)	(33,748)
Ending Balance	(359,276)	(31,443)
Accumulated Other Comprehensive Loss Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	11,037	171,224
Net change in unrealized gain or loss	(358,190)	(141,800)
Reclassification of net income or loss realized and included in earnings	1,707
Transfer of net unrealized loss from AFS to HTM securities portfolio	15,405
Income tax expense (benefit)	(76,981)	(31,862)
Ending Balance	(253,060)	61,286
Held to Maturity Securities Transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	153	276
Transfer of net unrealized loss from AFS to HTM securities portfolio	(15,405)
Amortization of unrealized net gain or loss on securities transferred to HTM	261	(56)
Income tax expense (benefit)	(3,418)	(13)
Ending Balance	(11,573)	233
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(80,946)	(125,573)
Reclassification of net income or loss realized and included in earnings	1,209	1,954
Income tax expense (benefit)	273	439
Ending Balance	(80,010)	(124,058)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	16,284	39,511
Net change in unrealized gain or loss	(33,182)	(4,152)
Reclassification of net income or loss realized and included in earnings	(6,754)	(6,136)
Income tax expense (benefit)	(9,014)	(2,312)
Ending Balance	(14,638)	31,535
Equity Method Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(463)	(5,369)
Net change in unrealized gain or loss	468	462
Reclassification of net income or loss realized and included in earnings		4,468
Ending Balance	$ 5	$ (439)