Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Unrealized gains (losses) on available-for-sale securities:
Balance, beginning of period	$ (10)	$ 166	$ (65)	$ (62)
Other comprehensive income before reclassifications	64	143	147	488
Amounts reclassified from accumulated other comprehensive income	(42)	(2)	(42)	(2)
Income taxes	(8)	(48)	(36)	(165)
Net current-period other comprehensive income	14	93	69	321
Balance, end of period	$ 4	$ 259	$ 4	$ 259