Equity Compensation Plans - Summary of Activity Related to ESPP (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Purchase Plan (ESPP) Activity [Roll Forward]
Balance at beginning of period	$ 6	$ 4	$ 3
Employee purchases	524	375	305
Cost of common stock issued	(526)	(373)	(304)
Balance at End of Period	$ 4	$ 6	$ 4