Income Taxes - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
State	$ 2	$ 2	$ 4
Foreign		301
Total current	2	303	4
Provision for (benefit from) income taxes	$ 2	$ 303	$ 4