Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Loss) by Component, Net of Tax (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]
Balance at beginning of period	$ 54,761	$ 54,007	$ 54,073	$ 52,839
Other comprehensive income before reclassification	10	461	268	1,340
Amounts reclassified from accumulated other comprehensive income (loss)	104	(53)	104	(55)
Net of tax	114	408	372	1,285
Balance at end of period	56,647	54,851	56,647	54,851
Unrealized Gains and Losses on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(421)	630	(679)	(247)
Other comprehensive income before reclassification	10	461	268	1,340
Amounts reclassified from accumulated other comprehensive income (loss)	104	(53)	104	(55)
Net of tax	114	408	372	1,285
Balance at end of period	(307)	1,038	(307)	1,038
Defined Benefit Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(3,812)	(3,514)	(3,812)	(3,514)
Other comprehensive income before reclassification	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net of tax	0	0	0	0
Balance at end of period	(3,812)	(3,514)	(3,812)	(3,514)
Totals
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(4,233)	(2,884)	(4,491)	(3,761)
Balance at end of period	$ (4,119)	$ (2,476)	$ (4,119)	$ (2,476)