Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal Income Tax Expense (Benefit)
Federal Income Tax Expense (Benefit), Continuing Operations	$ 0	$ 0	$ 0
State Income Tax Expense (Benefit)
Income tax expense related to state income tax	2,700	0	0
Foreign Income Tax Expense (Benefit)
Foreign Income Tax Expense (Benefit), Continuing Operations	0	0	0
Income tax expense	$ 2,685	$ 0	$ 0