Stockholders' Equity (Accumulated Other Comprehensive (Loss) Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Debt Securities, Available-for-sale, Adjustment, after Tax	$ 14,852	$ 5,560	$ (10,082)	$ (2,088)
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(3,872)	(3,958)	(3,711)	(4,256)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	(9,384)	(2,767)	860	1,129
Accumulated other comprehensive income (loss), net of deferred income taxes	1,336	(1,425)	(12,933)	$ (5,215)
Realized gain on sale of securities, net of tax	291	130	115
Other Comprehensive Income (Loss), Settlement and Curtailment Costs of Pension and Other Postretirement Benefit Plan Valuation, Net of Tax	833
Realized loss due to settlement and curtailment, net of tax	833		211
Amounts reclassified out of accumulated other comprehensive (loss) income per ASU 2018-02, defined benefit plans			0
Amounts reclassified out of accumulated other comprehensive (loss) income per ASU 2018-02, cash flow hedges			0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,637	11,638	(3,024)
Other comprehensive income (loss), net of reclassifications and tax	9,001	15,512	(3,089)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax	747	247	(334)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(6,617)	(3,627)	(269)
Amounts reclassified out of accumulated other comprehensive (loss) income per ASU 2016-01	$ 0	0	(5,020)
Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			$ (5,020)
Amounts reclassified out of accumulated other comprehensive (loss) income per ASU 2016-01		$ (5,000)