Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (1,673)	$ 900	$ 297
Other comprehensive income (loss):
Unrealized losses on investments	(10)
Total other comprehensive income (loss)	(10)
Comprehensive income (loss)	$ (1,683)	$ 900	$ 297