Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 80,069	$ (54,724)	$ (180,709)
Net change in unrealized gain (loss)	(211,580)	224,337	143,922
Reclassification of net gain (loss) realized and included in earnings	(15,485)	(10,983)	13,429
Valuation adjustments for employee benefit plans		(37,451)	2,398
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 loss on securities transferred to held to maturity	(158)	(470)	3,153
Income tax expense (benefit)	(40,348)	40,640	36,917
Ending Balance	(53,935)	80,069	(54,724)
Accumulated Other Comprehensive Loss Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	171,224	28,950	(50,125)
Net change in unrealized gain (loss)	(208,760)	183,441	115,413
Reclassification of net gain (loss) realized and included in earnings	2,166
Unrealized loss on securities transferred to available for sale			(13,236)
Income tax expense (benefit)	(46,407)	41,167	23,102
Ending Balance	11,037	171,224	28,950
Held to Maturity Securities Transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	276	639	(12,044)
Unrealized loss on securities transferred to available for sale			13,236
Amortization of unrealized net loss on securities transferred to held to maturity	(158)	(470)	3,153
Income tax expense (benefit)	(35)	(107)	3,706
Ending Balance	153	276	639
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(125,573)	(101,278)	(110,247)
Reclassification of net gain (loss) realized and included in earnings	4,555	6,368	9,174
Valuation adjustments for employee benefit plans		(37,451)	2,398
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)	12,799	(6,788)	2,603
Ending Balance	(80,946)	(125,573)	(101,278)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	39,511	17,399	(8,293)
Net change in unrealized gain (loss)	(3,258)	45,831	28,943
Reclassification of net gain (loss) realized and included in earnings	(26,674)	(17,351)	4,255
Income tax expense (benefit)	(6,705)	6,368	7,506
Ending Balance	16,284	39,511	17,399
Equity Method Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,369)	(434)
Net change in unrealized gain (loss)	438	(4,935)	(434)
Reclassification of net gain (loss) realized and included in earnings	4,468
Ending Balance	$ (463)	$ (5,369)	$ (434)