Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details)

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Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Jan. 01, 2018
Dec. 31, 2016
Dec. 31, 2015
New Accounting Pronouncement, Early Adoption [Line Items]        
Reserve for uncertain tax position     $ 1,946  
Decrease to accumulated deficit       $ (293,896)
Accumulated Deficit        
New Accounting Pronouncement, Early Adoption [Line Items]        
Decrease to accumulated deficit       $ (293,896)
Accounting Standards Update 2016-09        
New Accounting Pronouncement, Early Adoption [Line Items]        
Increase in deferred tax assets     $ 293,896  
Accounting Standards Update 2014-09 | Forecast        
New Accounting Pronouncement, Early Adoption [Line Items]        
Decrease in revenue, as a percent (less than) $ 90,000      
Accounting Standards Update 2014-09 | Subsequent Event | Accumulated Deficit        
New Accounting Pronouncement, Early Adoption [Line Items]        
Decrease to accumulated deficit   $ 19,000