Comprehensive Income - Components of AOCI (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 (AOCI)
Beginning balance			$ 145,625	$ 114,712
Other comprehensive loss before reclassification	$ 60	$ (412)	1,585	1,454
Amounts reclassified from AOCI	(27)	(252)	(165)	(543)
Total other comprehensive income	33	(664)	1,420	911
Ending balance	148,977	125,377	148,977	125,377
Unrealized gains (losses) on available for-sale securities
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	(9)	1,702	(1,598)	(363)
Other comprehensive loss before reclassification	96	(437)	1,895	1,990
Amounts reclassified from AOCI	(63)	(287)	(273)	(649)
Total other comprehensive income	33	(724)	1,622	1,341
Ending balance	24	978	24	978
Defined benefit pension plan items
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	(2,881)	(3,060)	(2,679)	(2,570)
Other comprehensive loss before reclassification	(36)	25	(310)	(536)
Amounts reclassified from AOCI	36	35	108	106
Total other comprehensive income	0	60	(202)	(430)
Ending balance	(2,881)	(3,000)	(2,881)	(3,000)
AOCI attributable to parent
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	(2,890)	(1,358)	(4,277)	(2,933)
Total other comprehensive income			1,420	911
Ending balance	$ (2,857)	$ (2,022)	$ (2,857)	$ (2,022)