Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies - Additional Information (Detail)

v3.10.0.1
Significant Accounting Policies - Additional Information (Detail)
12 Months Ended
Dec. 31, 2018
USD ($)
Segment
shares
Dec. 31, 2017
USD ($)
shares
Significant Accounting Policies [Line Items]    
Amortization period description The amortization period begins with the first month of availability on our service.  
Number of reporting unit | Segment 1  
Impairment of goodwill $ 0 $ 0
Impairment of long-lived assets 0 0
Advertising expense $ 46,300,000 $ 25,700,000
Defined contribution plan percentage employee's matching contribution 50.00%  
Defined contribution plan maximum annual matching contribution amount $ 3,000  
Common stock shares excluded from computation of dilutive earnings per share | shares 66,000 57,000
Impairment charges on cost method investments $ 0 $ 0
Defined Contribution Plan 401 (k) [Member]    
Significant Accounting Policies [Line Items]    
Defined contribution plan annual matching contribution amount $ 175,000 $ 100,000
Website Development Costs and Other Software [Member]    
Significant Accounting Policies [Line Items]    
Estimated useful life of property and equipment 3 years  
Minimum [Member]    
Significant Accounting Policies [Line Items]    
Estimated useful life of property and equipment 3 years  
License period or estimated useful life of media library 12 months  
Maximum [Member]    
Significant Accounting Policies [Line Items]    
Estimated useful life of property and equipment 45 years  
License period or estimated useful life of media library 90 months