Income Taxes - Deferred Tax Valuation Allowance (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Line Items]
Beginning balance	$ 64,482	$ 90,366	$ 59,349
Additions based on changes in deferred tax assets	25,932	2,717	25,193
Reductions based on changes in deferred tax assets	(74)	(28,601)
Increase in valuation allowance due to rate change from Tax Act			5,824
Ending balance	$ 90,340	$ 64,482	$ 90,366