Stockholders' Equity (Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income) (Details) - Amount Reclassified from Accumulated Other Comprehensive Income [Member] - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	[1]	$ (3,722)	$ (1,972)
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]	(591)	(755)
Tax effect	[1]	134	171
Net of tax	[1]	(457)	(584)
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]	(2,203)	(1,177)
Tax effect	[1]	498	267
Net of tax	[1]	(1,705)	(910)
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]	(610)	336
Tax effect	[1]	138	(76)
Net of tax	[1]	(472)	260
Amortization of loss on terminated cash flow hedges	[1]	(1,406)	(954)
Tax effect	[1]	318	216
Net of tax	[1]	$ (1,088)	$ (738)

[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).