Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current provision:
State	$ 0	$ 5	$ 5
Foreign	198	342	18
Total current provision	198	347	23
Deferred benefit:
Foreign	(9)	(8)	(6)
Total deferred benefit	(9)	(8)	(6)
Provision for income taxes	$ 189	$ 339	$ 17