Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (53,935)	$ 80,069	$ (54,724)
Net change in unrealized gain (loss)	(898,241)	(211,580)	224,337
Reclassification of net gain (loss) realized and included in earnings	(5,947)	(15,485)	(10,983)
Valuation adjustments for employee benefit plans	(24,139)		(37,451)
Valuation Adjustments to Pension Plan attributable to VERIP and Curtailment		59,606
Other valuation adjustments to employee benefit plans		(6,735)
Amortization of unrealized net gain (loss) on securities transferred to held to maturity	1,355	(158)	(470)
Income tax (expense) benefit	(208,725)	(40,348)	40,640
Ending Balance	(772,182)	(53,935)	80,069
Accumulated Other Comprehensive Loss Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	11,037	171,224	28,950
Net change in unrealized gain (loss)	(785,538)	(208,760)	183,441
Reclassification of net gain (loss) realized and included in earnings	1,707	2,166
Transfer of net unrealized loss from AFS to HTM securities portfolio	15,405
Income tax (expense) benefit	172,981	46,407	(41,167)
Ending Balance	(584,408)	11,037	171,224
Held to Maturity Securities Transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	153	276	639
Transfer of net unrealized loss from AFS to HTM securities portfolio	(15,405)
Amortization of unrealized net gain (loss) on securities transferred to held to maturity	1,355	(158)	(470)
Income tax (expense) benefit	3,163	35	107
Ending Balance	(10,734)	153	276
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(80,946)	(125,573)	(101,278)
Reclassification of net gain (loss) realized and included in earnings	2,274	4,555	6,368
Valuation adjustments for employee benefit plans	(24,139)		(37,451)
Valuation Adjustments to Pension Plan attributable to VERIP and Curtailment		59,606
Other valuation adjustments to employee benefit plans		(6,735)
Income tax (expense) benefit	4,859	(12,799)	6,788
Ending Balance	(97,952)	(80,946)	(125,573)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	16,284	39,511	17,399
Net change in unrealized gain (loss)	(113,171)	(3,258)	45,831
Reclassification of net gain (loss) realized and included in earnings	(9,928)	(26,674)	(17,351)
Income tax (expense) benefit	27,722	6,705	(6,368)
Ending Balance	(79,093)	16,284	39,511
Equity Method Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(463)	(5,369)	(434)
Net change in unrealized gain (loss)	468	438	(4,935)
Reclassification of net gain (loss) realized and included in earnings		4,468
Ending Balance	$ 5	$ (463)	$ (5,369)