Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 458,308	$ 432,686
Other comprehensive income (loss) - before reclassifications	(5,302)	707
Amount reclassified from accumulated other comprehensive income	(1,382)	(24)
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect	0
Other comprehensive (loss) income, net of tax	(5,338)	683
Balance	462,097	438,700
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(1,806)	(6,251)
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect	(1,346)
Other comprehensive (loss) income, net of tax	(5,338)	683
Balance	(8,490)	(5,568)
Net Unrealized Holding Gain (Loss) on Securities Available for Sale, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(5,030)	(6,762)
Other comprehensive income (loss) - before reclassifications	(5,302)	707
Amount reclassified from accumulated other comprehensive income	0	0
Other comprehensive (loss) income, net of tax	(5,302)	707
Balance	(10,332)	(6,055)
Net Change in Net Actuarial (Gain) loss and Prior Service Cost on Pension and Adjustment Postretirement Benefit Plans, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	3,224	511
Other comprehensive income (loss) - before reclassifications	0	0
Amount reclassified from accumulated other comprehensive income	(36)	(24)
Other comprehensive (loss) income, net of tax	(36)	(24)
Balance	$ 3,188	$ 487