Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Tax act, transition tax expense	$ 6,100
Tax act, transition tax obligation		$ 18,800
Tax act, deferred tax assets		33,000
Tax act, discrete deferred tax benefit		11,000
Valuation allowance	56,724	35,132
Unrecognized tax benefits	74,436	48,835	$ 26,915	$ 22,239
Unrecognized tax benefits that would affect effective tax rate	35,700	26,800	$ 13,900
Accrued interest and penalties	900	400
Liability for interest and penalties	1,900	$ 1,000
Research Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Tax credit carryforward	1,200
Domestic Tax Authority
Income Tax Disclosure [Line Items]
Operating loss carryforwards	73,700
Tax credit carryforward	22,200
State and Local Jurisdiction
Income Tax Disclosure [Line Items]
Operating loss carryforwards	38,400
Tax credit carryforward	84,200
Foreign Tax Authority
Income Tax Disclosure [Line Items]
Operating loss carryforwards	$ 23,800