Accumulated Other Comprehensive Income - Components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017		Mar. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 201,380	[1]	$ 197,835
Net unrealized gains (losses) on securities available for sale, net of tax	657		1,444
Reclassification adjustment for gains on sales of securities, net of tax	(168)		(238)
Ending Balance	204,241		200,443
Net unrealized gains (losses) on securities available for sale, tax	354		778
Reclassification adjustment for gains on sales of securities, tax	(91)		(128)
Net Unrealized Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(150)		4,122
Net unrealized gains (losses) on securities available for sale, net of tax	657		1,444
Reclassification adjustment for gains on sales of securities, net of tax	(168)		(238)
Ending Balance	339		5,328
Adjustments Related to Pension Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,724)		(1,832)
Ending Balance	(1,724)		(1,832)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,874)		2,290
Ending Balance	$ (1,385)		$ 3,496

[1] Derived from audited consolidated financial statements.