Stockholders' Equity (Accumulated Other Comprehensive (Loss) Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment in Net Income, Net of Tax			$ 1,442
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	$ 645		645		$ 1,186
Accumulated Other Comprehensive (Loss) Income [Roll Forward]
Unrealized Gain on Securities			581
Realized gain on sale of securities, net of tax			(1,442)
Other comprehensive income (loss), net of reclassifications and tax			3,542
Unrealized Gain on Securities	2,681		2,681
Unrecognized Net Pension and Postretirement Costs			3,321
Other comprehensive income (loss), net of reclassifications and tax			46
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(41)	$ 44	(541)	$ (120)
Unrecognized Net Pension and Postretirement Costs	(3,275)		(3,275)
Accumulated Other Comprehensive Income (Loss)			(1,554)
Other comprehensive income (loss), net of reclassifications and tax			3,047
Accumulated Other Comprehensive Income (Loss)	$ 51		$ 51