Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Provisional income tax expense related to repatriation of foreign earnings			$ (43,700)
Expected repatriation of foreign earnings related to the Tax Act	$ 9,900
State and foreign net operating loss carry forwards		$ 61,009	38,023
State tax credits		23,195	9,965
Valuation allowance		40,966	21,755
Increase in valuation allowance		(19,200)
Unrecognized tax benefits that would impact effective tax rate		4,000
Unrecognized tax benefit with uncertainty about timing of deductibility		5,400
Accrued interest		$ 800	$ 2,000
Minimum
Income Taxes [Line Items]
Period of income tax returns examination after filing		3 years
Maximum
Income Taxes [Line Items]
Period of income tax returns examination after filing		5 years

Income Tax Examination Extended Years Under Examination

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Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit)

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Tax Cuts and Jobs Act of 2017, Repatriation of Foreign Earnings

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Unrecognized tax benefit with uncertainty about timing of deductibility

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of interest expense accrued for an underpayment of income taxes.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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