Stockholders' Equity (Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items		$ (10,251)
Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items		(10,251)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	[1]	2,171	$ (7,495)
Reclassification out of Accumulated Other Comprehensive Income | Held to Maturity Securities Transferred from AFS [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized net gain or loss or gain on securities transferred to HTM	[1]	289	(1,481)
Tax effect	[1]	(65)	335
Net of tax	[1]	224	(1,146)
Reclassification out of Accumulated Other Comprehensive Income | Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items	[1],[2]	(2,944)	(4,527)
Tax effect	[1]	666	1,023
Net of tax	[1]	(2,278)	(3,504)
Reclassification out of Accumulated Other Comprehensive Income | Gains and Losses on Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification of unrealized gain (loss) on cash flow hedges	[1]	6,550	(1,204)
Tax effect	[1]	(1,482)	272
Net of tax	[1]	5,068	(932)
Amortization of loss on terminated cash flow hedges	[1]	(1,089)	(2,472)
Tax effect	[1]	246	559
Net of tax	[1]	$ (843)	$ (1,913)

[1] Amounts in parentheses indicate reduction in net income.

[2] These AOCI components are included in the computation of net periodic pension and post-retirement cost that is reported with other noninterest expense (see Note 12 – Retirement Plans for additional details).