Stockholders' Equity (Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items			$ 17,315
Amount Reclassified from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	[1]	$ (30,468)	(6,064)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Available for Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain (loss) on sale of AFS securities	[1]	(25,480)
Tax effect	[1]	5,720
Net of tax	[1]	(19,760)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | HTM 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]	(3,296)	(3,786)
Tax effect	[1]	755	1,393
Net of tax	[1]	(2,541)	(2,393)
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]	(4,989)	(5,201)
Tax effect	[1]	1,122	1,898
Net of tax	[1]	(3,867)	(3,303)
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 on cash flow hedges	[1]	1,072
Tax effect	[1]	(244)
Net of tax	[1]	828
Amortization of loss on terminated cash flash hedges	[1]	(5,569)	(600)
Tax effect	[1]	1,269	232
Net of tax	[1]	$ (4,300)	$ (368)

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