Geographical Information - Property and Equipment, Net and Operating Lease Assets, Presented by Principal Geographic Area (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	[1]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	$ 225,010	$ 33,046
UNITED STATES
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	141,721	25,887
International
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	$ 83,289	$ 7,159

[1] As a result of the Company’s adoption of ASC 842 on January 1, 2019, the December 31, 2018 balance excludes operating lease assets. Refer to Note 2—Basis of Presentation and Summary of Significant Accounting Policies for additional information regarding the Company’s adoption of ASC 842.