Income Taxes - Effective Income Tax Reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the U.S. federal statutory tax rate to the actual tax rate is as follows:
Statutory U.S. federal income tax rate	21.00%	21.00%	21.00%
Foreign earnings at rates different than U.S. federal rate	(0.20%)	(3.70%)	(1.50%)
Valuation allowance adjustments	(16.70%)	(31.00%)	(16.80%)
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Percent	0	0	(0.031)
Effective Income Tax Rate Reconciliation, Adjustment Permanent Items, Percent	(1.90%)	(3.60%)	(2.50%)
Effective Income Tax Rate Reconciliation, Reduction of UTBs, Percent	0.30%	6.20%	0.00%
Effective Income Tax Rate Reconciliation, Goodwill Impairment, Percent	(2.20%)	0.00%	0.00%
Other	(1.00%)	1.90%	(1.00%)
Effective income tax rate	(0.70%)	(9.20%)	(3.90%)