Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Provisional tax amounts from Tax Act	$ 51,800,000	$ 51,800,000
Transition tax	18,800,000	18,800,000
Re-measurement of deferred tax assets and liabilities		33,000,000
Valuation allowance	35,132,000	35,132,000	$ 16,894,000
Increase in valuation allowance		18,200,000	4,200,000
Undistributed earnings	82,300,000	82,300,000	36,400,000	$ 16,400,000
Unrecognized tax benefits	48,835,000	48,835,000	26,915,000	22,239,000	$ 21,322,000
Unrecognized tax benefits that would affect effective tax rate	23,500,000	23,500,000	13,900,000	$ 13,000,000
Accrued interest and penalties		400,000	500,000
Liability for interest and penalties	1,000,000	1,000,000	$ 600,000
Research Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Tax credit carryforward	1,200,000	1,200,000
Domestic Tax Authority
Income Tax Disclosure [Line Items]
Operating loss carryforwards	0	0
Tax credit carryforward	200,000.0	200,000.0
Foreign Tax Authority
Income Tax Disclosure [Line Items]
Operating loss carryforwards	12,800,000	12,800,000
State and Local Jurisdiction
Income Tax Disclosure [Line Items]
Operating loss carryforwards	0	0
Tax credit carryforward	$ 59,500,000	$ 59,500,000