Equity Compensation Plans - Summary of Activity Related to ESPP (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Stock Purchase Plan (ESPP) Activity [Roll Forward]
Balance at beginning of period	$ 18	$ 3	$ 3
Employee purchases	290	475	494
Cost of common stock issued	(305)	(460)	(494)
Balance at End of Period	$ 3	$ 18	$ 3