Income Taxes - Difference in Federal and Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of difference between the federal statutory tax rate and the effective tax rate
Federal statutory rate	21.00%	21.00%	35.00%
State income taxes, net of federal benefit	2.80%	4.30%	5.10%
Foreign income tax	(6.60%)	(6.00%)	(5.30%)
Income Tax Refunds	0.00%	3.60%	0.00%
Research and development tax credits	0.30%	1.90%	0.60%
Non-Deductible components of Convertible Debt	0.00%	(0.20%)	0.10%
Valuation allowance	(17.90%)	(7.10%)	(28.40%)
Rate change effect	0.40%	8.10%	(10.80%)
Non-deductible items	(0.70%)	(2.90%)	(1.90%)
Unrecognized tax benefits	0.00%	(1.80%)	(0.70%)
Impairments	(1.60%)	0.00%	0.00%
Other	0.00%	(0.70%)	(0.40%)
Total	(2.30%)	20.20%	(6.70%)