Accumulated Other Comprehensive (Loss) Income - Components of Accumulated Other Comprehensive (Loss) Income, Net of Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance			$ (19,454)	$ (16,708)
Net Change	$ 839	$ 166	3,111	2,504
Ending balance	(16,343)	(14,204)	(16,343)	(14,204)
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance			(4,988)	(592)
Net Change			2,624	2,381
Ending balance	(2,364)	1,789	(2,364)	1,789
Net Change Related to Derivative Used for Cash Flow Hedge [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance			(141)	(285)
Net Change			28	(382)
Ending balance	(113)	(667)	(113)	(667)
Net Change Related to Defined Benefit Pension Plan [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance			(14,325)	(15,831)
Net Change			459	505
Ending balance	$ (13,866)	$ (15,326)	$ (13,866)	$ (15,326)