v3.19.1
Summary of Significant Accounting Policies - Summary of Property and Equipment Estimated Useful Lives (Detail)
12 Months Ended
Dec. 31, 2018
Computer Equipment [Member]  
Significant Accounting Policies [Line Items]  
Property, plant and equipment, useful life 3 years
Software [Member]  
Significant Accounting Policies [Line Items]  
Property, plant and equipment, useful life 3 years
Furniture and Fixtures [Member]  
Significant Accounting Policies [Line Items]  
Property, plant and equipment, useful life 5 years
Leasehold Improvements [Member]  
Significant Accounting Policies [Line Items]  
Property, plant and equipment, useful life Shorter of lease term or estimated useful life