Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Activity for All RSUs (Details)

v3.8.0.1
Stock-Based Compensation - Summary of Activity for All RSUs (Details) - Restricted Stock Units (RSUs) - $ / shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares, Unvested, Balance 4,106,000 1,506,000  
Shares, Granted 3,540,000 3,363,000 947,342
Shares, Issued (1,115,000) (422,000)  
Shares, Cancelled / forfeited (1,201,000) (341,000)  
Shares, Unvested, Balance 5,330,000 4,106,000 1,506,000
Weighted-average grant date fair value, Unvested, Balance $ 6.87 $ 10.44  
Weighted-average grant date fair value, Granted 5.30 5.82  
Weighted-average grant date fair value, Issued 7.36 9.55  
Weighted-average grant date fair value, Cancelled / forfeited 5.81 6.80  
Weighted-average grant date fair value, Unvested, Balance $ 5.82 $ 6.87 $ 10.44