Stockholders' Equity (Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items		$ 7,015	$ 9,039
Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items		7,015	9,039
Amount Reclassified from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	[1]	(10,774)	(6,951)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Held to Maturity Securities Transferred from AFS [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized net loss on securities transferred to HTM	[1]	(2,435)	(2,427)
Tax effect	[1]	551	550
Net of tax	[1]	(1,884)	(1,877)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | 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]	(6,851)	(3,719)
Tax effect	[1]	1,546	842
Net of tax	[1]	(5,305)	(2,877)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | 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]	(1,200)	1,264
Tax effect	[1]	271	(286)
Net of tax	[1]	(929)	978
Amortization of loss on terminated cash flow hedges	[1]	(3,432)	(4,105)
Tax effect	[1]	776	930
Net of tax	[1]	$ (2,656)	$ (3,175)

[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 employee benefits expense (see Note 12 – Retirement Plans for additional details).