Stockholders' Equity (Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities		$ (1,158)	$ (802)	$ (2,960)	$ (2,208)
Available for Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities				1,435	165
HTM Securities Transferred from AFS [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities
Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities				(4,395)	(2,373)
Amount Reclassified from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	[1]			(3,631)	(3,091)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Available for Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities	[1]			1,435	165
Tax effect	[1]			502	58
Net of tax	[1]			933	107
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]			(2,736)	(2,609)
Tax effect	[1]			1,029	953
Net of tax	[1]			(1,707)	(1,656)
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]			(4,395)	(2,373)
Tax effect	[1]			1,538	831
Net of tax	[1]			$ (2,857)	$ (1,542)

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

[2] These accumulated other comprehensive income components are included in the computation of net periodic pension and post-retirement cost that is reported with employee benefits expense (see Note 11 for additional details).