Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ (772,182)	$ (53,935)
Net change in unrealized gain (loss)			(187,089)	(961,892)
Reclassification of net income or loss realized and included in earnings	$ 12,854	$ (1,441)	33,619	(10,849)
Valuation adjustments to employee benefit plans			(7,307)	(8,397)
Amortization of unrealized net loss on securities transferred to HTM	421	434	1,343	961
Income tax (expense) benefit	38,833	83,250	36,622	221,331
Ending Balance	(894,994)	(812,781)	(894,994)	(812,781)
Accumulated Other Comprehensive Loss Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(584,408)	11,037
Net change in unrealized gain (loss)			(142,980)	(844,250)
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			32,757	186,685
Ending Balance	(694,631)	(629,416)	(694,631)	(629,416)
Held to Maturity Securities Transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(10,734)	153
Transfer of net unrealized loss from AFS to HTM securities portfolio				(15,405)
Amortization of unrealized net loss on securities transferred to HTM			1,343	961
Income tax (expense) benefit			(302)	3,260
Ending Balance	(9,693)	(11,031)	(9,693)	(11,031)
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(97,952)	(80,946)
Reclassification of net income or loss realized and included in earnings			5,010	1,963
Valuation adjustments to employee benefit plans			(7,307)	(8,397)
Income tax (expense) benefit			517	1,452
Ending Balance	(99,732)	(85,928)	(99,732)	(85,928)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(79,093)	16,284
Net change in unrealized gain (loss)			(44,823)	(118,110)
Reclassification of net income or loss realized and included in earnings			28,609	(14,519)
Income tax (expense) benefit			3,650	29,934
Ending Balance	(91,657)	(86,411)	(91,657)	(86,411)
Equity Method Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			5	(463)
Net change in unrealized gain (loss)			714	468
Ending Balance	$ 719	$ 5	$ 719	$ 5