Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			$ 432,686	$ 413,310
Other comprehensive income (loss) - before reclassifications	$ 562	$ (75)	3,275	7,483
Amount reclassified from accumulated other comprehensive income	(29)	8	(84)	(376)
Other comprehensive income, net of tax	533	(67)	3,191	7,109
Balance	454,928	435,608	454,928	435,608
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(3,593)	2,395	(6,251)	(4,781)
Other comprehensive income, net of tax			3,191	7,109
Balance	(3,060)	2,328	(3,060)	2,328
Net Unrealized Holding Gain (Loss) on Securities Available for Sale, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(4,049)	2,667	(6,762)	(4,492)
Other comprehensive income (loss) - before reclassifications	562	(75)	3,275	7,483
Amount reclassified from accumulated other comprehensive income	0	0	0	(401)
Other comprehensive income, net of tax	562	(75)	3,275	7,084
Balance	(3,487)	2,592	(3,487)	2,592
Net Change in Net Actuarial Gain and Prior Service Cost on Pension and Postretirement Benefit Plans, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	456	(272)	511	(289)
Other comprehensive income (loss) - before reclassifications	0	0	0	0
Amount reclassified from accumulated other comprehensive income	(29)	8	(84)	25
Other comprehensive income, net of tax	(29)	8	(84)	25
Balance	$ 427	$ (264)	$ 427	$ (264)