Comprehensive Income/Loss (Comprehensive Income/(Loss) Presented Net of Taxes) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax		$ 31,981	$ 4,572
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), after Adjustments, Tax		(8,997)	(1,287)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax		22,984	3,285
COMPREHENSIVE INCOME
Change in fair value of securities available for sale, pre tax amount		12,123	6,178
Change in fair value of securities available for sale, tax (expense) benefit		(2,776)	(1,449)
Change in fair value of securities available for sale, after tax amount		9,347	4,729
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax		0	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax		0	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		0	0
Change in fair value of securities available for sale, pre tax amount		12,123	6,178
Change in fair value of securities available for sale, tax (expense) benefit		(2,776)	(1,449)
Change in fair value of securities available for sale, after tax amount		9,347	4,729
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax		33,567	4,996
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), before Adjustments, Tax		(9,443)	(1,406)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax		24,124	3,590
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax		1,586	424
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), Adjustments, Tax		(446)	(119)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax		1,140	305
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		(1,389)	(11)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax		391	3
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax		(998)	(8)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		245	(2)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax		(69)	1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax		176	(1)
Amortization of certain costs included in net periodic retirement costs, pre tax amount		69	69
Amortization of certain costs included in net periodic retirement costs, tax (expense) benefit		(19)	(20)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax		50	49
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	(1,075)	56
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	[1]	303	(16)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	[1]	(772)	40
Total other comprehensive income, pre tax amount		43,029	10,806
Total other comprehensive income, tax (expense) benefit		(11,470)	(2,752)
Total other comprehensive income, after tax amount		$ 31,559	$ 8,054

[1] The amortization of prior service costs is included in the computation of net periodic pension cost as disclosed in the Employee Benefit Plans footnote in the Company's Annual Report on Form 10-K for the year ended December 31, 2019, filed with the Securities and Exchange Commission.