Accumulated Other Comprehensive Income - Components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			$ 201,380	[1]	$ 197,835
Net unrealized gains on securities available for sale, net of tax	$ 572	$ 379	1,229		1,823
Reclassification adjustment for gains on sales of securities, net of tax	(215)	(144)	(383)		(382)
Ending Balance	207,053	202,704	207,053		202,704
Net unrealized gains (losses) on securities available for sale, tax	307	204	661		982
Reclassification adjustment for gains on sales of securities, tax	(116)	(78)	(207)		(206)
Net Unrealized Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	339	5,328	(150)		4,122
Net unrealized gains on securities available for sale, net of tax	572	379	1,229		1,823
Reclassification adjustment for gains on sales of securities, net of tax	(215)	(144)	(383)		(382)
Ending Balance	696	5,563	696		5,563
Adjustments Related to Pension Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,724)	(1,832)	(1,724)		(1,832)
Ending Balance	(1,724)	(1,832)	(1,724)		(1,832)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,385)	3,496	(1,874)		2,290
Ending Balance	$ (1,028)	$ 3,731	$ (1,028)		$ 3,731

[1] Derived from audited consolidated financial statements.