Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	$ 296,456	$ 275,830	$ 285,143
Other comprehensive (loss) income before reclassifications	(1,005)	535	(16)
Amounts reclassified from accumulated other comprehensive (loss) income	143	(17)	(8)
Net current period change in other comprehensive (loss) income	(862)	518	(24)
Balance	338,842	296,456	275,830
Realized (loss) gain on sales of available-for-sale securities	(200)	100	100
Other comprehensive income tax benefit	500	300	100
Accumulated Other Comprehensive (Loss) Income, Net of Taxes
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	543	25	49
Balance	$ (319)	$ 543	$ 25