Income Taxes - Reconciliation of income tax at the federal statutory rate to the actual effective income tax rate (benefit) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal statutory rate	(21.00%)	(35.00%)	(35.00%)
Foreign rate differential	(3.00%)	1.50%	2.10%
State income taxes, net of federal benefit	(1.30%)	(2.50%)	(3.20%)
State income taxes, net of federal benefit	(0.80%)	(3.00%)	(0.00%)
Nondeductible transaction costs	0.50%	1.40%	1.90%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent	1.10%	(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Disposition of Asset, Percent	10.40%	(0.00%)	(0.00%)
EffectiveIncomeTaxRateReconciliationTaxIndemnificationCharges	0.095	(0.013)	0.015
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent	(1.40%)	(0.00%)	(0.00%)
Other differences	2.70%	(2.70%)	2.70%
Effective Income Tax Rate Reconciliation, Witholding Tax Adjustment, Percent	0.017	0.025	0.015
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	(12.00%)	(2.10%)	(0.70%)
Effective Income Tax Rate Reconciliation, Uncertain Tax Positions, Percent	(38.00%)	7.30%	1.90%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	22.90%	47.20%	23.70%
Rate change - impact of the Tax Act	(0.00%)	19.90%	(0.00%)
Repatriation tax - impact of the Tax Act	(1.00%)	4.10%	(0.00%)
Tax credits - impact of the Tax Act	0.60%	(6.00%)	(0.00%)
Valuation allowance - impact of the Tax Act	0.40%	(35.30%)	(0.00%)
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent	(28.70%)	(4.00%)	(3.60%)