Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ (621,127)	$ (772,182)
Net change in unrealized gain (loss)			121,552	(187,089)
Reclassification of net loss realized and included in earnings	$ 13,964	$ 12,854	41,689	33,619
Valuation adjustments to employee benefit plans			22,014	(7,307)
Amortization of unrealized net loss on securities transferred to HTM	461	421	1,279	1,343
Income tax (expense) benefit	(51,688)	38,833	(40,903)	36,622
Ending Balance	(475,496)	(894,994)	(475,496)	(894,994)
Accumulated Other Comprehensive Loss Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(450,748)	(584,408)
Net change in unrealized gain (loss)			132,391	(142,980)
Income tax (expense) benefit			(28,958)	32,757
Ending Balance	(347,315)	(694,631)	(347,315)	(694,631)
Held to Maturity Securities Transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(9,385)	(10,734)
Amortization of unrealized net loss on securities transferred to HTM			1,279	1,343
Income tax (expense) benefit			(268)	(302)
Ending Balance	(8,374)	(9,693)	(8,374)	(9,693)
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(103,061)	(97,952)
Reclassification of net loss realized and included in earnings			3,569	5,010
Valuation adjustments to employee benefit plans			22,014	(7,307)
Income tax (expense) benefit			(5,555)	517
Ending Balance	(83,033)	(99,732)	(83,033)	(99,732)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(58,306)	(79,093)
Net change in unrealized gain (loss)			(10,495)	(44,823)
Reclassification of net loss realized and included in earnings			38,120	28,609
Income tax (expense) benefit			(6,122)	3,650
Ending Balance	(36,803)	(91,657)	(36,803)	(91,657)
Equity Method Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			373	5
Net change in unrealized gain (loss)			(344)	714
Ending Balance	$ 29	$ 719	$ 29	$ 719