Equity Compensation Plans - Summary of Activity Related to ESPP (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Stock Purchase Plan (ESPP) Activity [Roll Forward]
Balance at beginning of period	$ 4	$ 6	$ 4
Employee purchases	347	524	375
Cost of common stock issued	(334)	(526)	(373)
Balance at End of Period	$ 17	$ 4	$ 6