Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss And Tax Credit Carryforward [Line Items]
Valuation allowance	$ 81,127,000	$ 34,664,000
Increase (decrease) in valuation allowance	46,500,000	(14,500,000)
Changes to amounts recorded for remeasurement of certain deferred tax assets and liabilities	0
Change in valuation allowance adjustment on tax reform changes in the treatment of indefinite-lived attributes	0
Final amount related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings	400,000
Operating Loss carryforward offset to final amount related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings	400,000
Undistributed foreign earnings	0
Additional outside basis differences on investments in foreign subsidiaries	4,800,000
Cumulative unrecognized tax benefits	3,351,000	$ 1,486,000	$ 4,273,000
Federal
Operating Loss And Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 162,200,000
Operating loss carryforwards, expiration year	2019
Federal | Research and Development
Operating Loss And Tax Credit Carryforward [Line Items]
Research and development credits	$ 14,700,000
Research and development credits, expiration year	2032
State
Operating Loss And Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 63,800,000
Operating loss carryforwards, expiration year	2019
State | Research and Development
Operating Loss And Tax Credit Carryforward [Line Items]
Research and development credits	$ 10,800,000
Foreign | Research and Development
Operating Loss And Tax Credit Carryforward [Line Items]
Research and development credits	$ 1,100,000
Research and development credits, expiration year	2037