Income Taxes - Summary of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 0	$ 0
Foreign	0
State	0	13
Current income tax expense (benefit)	0	13
Deferred:
Federal	0	0
Foreign	0	0
State	0	0
Deferred income tax expense (benefit)	0	0
Income tax expense	$ 0	$ 13