Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current expense (benefit):
Federal	$ 0	$ 0	$ 0
State	0	0	0
Foreign	68	80	0
Total current tax expense (benefit)	68	80	0
Deferred expense (benefit):
Federal	0	0	0
State	0	0	0
Foreign	(3)	(36)	0
Total deferred tax expense (benefit)	(3)	(36)	0
Total Tax Expense (benefit)	$ 65	$ 44	$ 0