Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ (621,127)	$ (772,182)
Net change in unrealized gain (loss)			(98,151)	(2,559)
Reclassification of net loss realized and included in earnings	$ 14,148	$ 11,245	27,725	20,765
Valuation adjustments to employee benefit plans			22,014	(7,521)
Amortization of unrealized net loss on securities transferred to HTM	390	428	818	922
Income tax (expense) benefit	1,393	22,194	10,785	(2,211)
Ending Balance	(657,936)	(762,786)	(657,936)	(762,786)
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)			(59,111)	17,678
Income tax (expense) benefit			13,450	(3,737)
Ending Balance	(496,409)	(570,467)	(496,409)	(570,467)
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			818	922
Income tax (expense) benefit			(184)	(207)
Ending Balance	(8,751)	(10,019)	(8,751)	(10,019)
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			2,254	3,272
Valuation adjustments to employee benefit plans			22,014	(7,521)
Income tax (expense) benefit			(5,453)	956
Ending Balance	(84,246)	(101,245)	(84,246)	(101,245)
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)			(38,696)	(20,943)
Reclassification of net loss realized and included in earnings			25,471	17,493
Income tax (expense) benefit			2,972	777
Ending Balance	(68,559)	(81,766)	(68,559)	(81,766)
Equity Method Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			373	5
Net change in unrealized gain (loss)			(344)	706
Ending Balance	$ 29	$ 711	$ 29	$ 711