Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Unrealized gains (losses) on available-for-sale securities:
Balance beginning	$ (62)	$ (1)
Other comprehensive income (loss) before reclassifications	1	(95)
Amounts reclassified from accumulated other comprehensive loss	(6)
Income taxes	2	34
Net current-period other comprehensive income	(3)	(61)
Balance ending	$ (65)	$ (62)