Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Details)

v3.8.0.1
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Other Income and Expenses [Abstract]        
Advertising expense $ 262,701 $ 226,969 $ 206,351  
Research and development expense 96,917 69,025 54,933  
Stockholders’ (deficit) equity (1,523,874) (792,015) (166,491) $ 1,309,837
Foreign currency translation adjustment, net of tax 18,546 363 (100)  
Foreign currency translation adjustment, tax $ 11,286      
Minimum        
Deferred Revenue Arrangement [Line Items]        
Length of prepaid subscriptions, term 3 months      
Maximum        
Deferred Revenue Arrangement [Line Items]        
Length of prepaid subscriptions, term 12 months      
Accumulated Other Comprehensive (Loss) Income        
Other Income and Expenses [Abstract]        
Stockholders’ (deficit) equity $ 18,407 $ (139) $ (502) $ (402)