v3.20.4
Significant Accounting Policies and Basis of Presentation - Additional Information (Details)
 12 Months Ended
Dec. 31, 2020
USD ($)
FinancialInstitution
Dec. 31, 2019
USD ($)
FinancialInstitution
Customer
Dec. 31, 2018
USD ($)
Jan. 01, 2020
USD ($)
Summary Of Significant Accounting Policies [Line Items]        
Foreign currency gains (loss) $ 1,300,000 $ (200,000) $ (500,000)  
Impairment of goodwill 0 0 0  
Impairment of intangible assets 0 0    
Impairment of capitalized licensed content assets $ 0 0    
Lessee, operating lease, existence of option to extend true      
Lessee, operating lease, existence of option to terminate true      
Advertising costs $ 7,100,000 7,300,000 3,000,000.0  
Cumulative-effect adjustment to accumulated deficit $ 332,406,000 313,833,000    
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2016-13        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment | Revision of Prior Period, Adjustment        
Summary Of Significant Accounting Policies [Line Items]        
Cumulative-effect adjustment to accumulated deficit       $ 1,100,000
Accounting Standards Update 2019-02        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2018-15        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2018-13        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2017-04        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2019-04        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2020-02        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Accounting Standards Update 2020-03        
Summary Of Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted [true false] true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect [true false] true      
Leasehold Improvements        
Summary Of Significant Accounting Policies [Line Items]        
Property and equipment, estimated useful lives description shorter of the lease term or their estimated useful lives, which range from five to ten years      
Website and Internal-Use Software        
Summary Of Significant Accounting Policies [Line Items]        
Capitalized costs $ 2,200,000 100,000 1,000,000.0  
Amortized expenses $ 500,000 $ 1,600,000 $ 2,000,000.0  
Maximum        
Summary Of Significant Accounting Policies [Line Items]        
Business combination measurement period from acquisition 1 year      
Property and equipment, estimated useful lives 5 years      
Maximum | Leasehold Improvements        
Summary Of Significant Accounting Policies [Line Items]        
Property and equipment, estimated useful lives 10 years      
Maximum | Website and Internal-Use Software        
Summary Of Significant Accounting Policies [Line Items]        
Estimated useful life 3 years      
Minimum        
Summary Of Significant Accounting Policies [Line Items]        
Property and equipment, estimated useful lives 18 months      
Minimum | Leasehold Improvements        
Summary Of Significant Accounting Policies [Line Items]        
Property and equipment, estimated useful lives 5 years      
Minimum | Website and Internal-Use Software        
Summary Of Significant Accounting Policies [Line Items]        
Estimated useful life 2 years      
Customer Concentration Risk | Net Accounts Receivable        
Summary Of Significant Accounting Policies [Line Items]        
Number of customers accounted for 10% or more | Customer   0    
Customer 1        
Summary Of Significant Accounting Policies [Line Items]        
Number of financial institutions which manage cash balances | FinancialInstitution 2 2    
Customer 2        
Summary Of Significant Accounting Policies [Line Items]        
Number of financial institutions which manage cash balances | FinancialInstitution 2 2    
Customer H | Customer Concentration Risk | Net Accounts Receivable        
Summary Of Significant Accounting Policies [Line Items]        
Concentration risk percentage 11.00%      
Cash, Cash Equivalents and Short-term Investment | Customer 1        
Summary Of Significant Accounting Policies [Line Items]        
Concentration risk percentage 46.00% 65.00%    
Cash, Cash Equivalents and Short-term Investment | Customer 2        
Summary Of Significant Accounting Policies [Line Items]        
Concentration risk percentage 26.00% 34.00%