Share-Based Compensation - Additional Information (Details)
1 Months Ended 3 Months Ended 12 Months Ended
Aug. 31, 2015
shares
Sep. 30, 2015
$ / shares
shares
Jun. 30, 2014
employee
Mar. 31, 2014
Jun. 30, 2013
employee
Dec. 31, 2015
USD ($)
plan
$ / shares
shares
Dec. 31, 2014
USD ($)
employee
$ / shares
shares
Dec. 31, 2013
USD ($)
event
employee
$ / shares
shares
Aug. 07, 2015
$ / shares
Dec. 31, 2012
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of stock incentive plans | plan           2        
Aggregate number of shares subject to outstanding options and RSAs under both plans           16,012,417        
Award expiration period           10 years        
Exercise of vested stock options (in shares)           1,374,438 0 9,400    
Restricted stock awarded (in shares)   683,401                
Outstanding options (in shares)           15,260,266 19,924,405 20,540,273   17,707,139
Unrecognized share-based compensation expense | $           $ 47,200,000 $ 42,800,000 $ 43,300,000    
Unrecognized stock-based compensation expense, weighted-average recognition period           2 years 10 months 12 days 3 years 2 months 12 days 2 years 9 months 18 days    
Weighted-average grant date fair value of options granted (in dollars per share) | $ / shares           $ 2.78 $ 4.40 $ 5.19    
Total intrinsic value of options exercised | $           $ 4,900,000 $ 0 $ 100,000    
Total fair value of options vested | $           $ 14,900,000 $ 22,900,000 $ 27,100,000    
Options granted (in shares)           2,231,504 4,406,856 8,345,437    
Weighted-average exercise price, granted (in dollars per share) | $ / shares           $ 5.60 $ 8.78 $ 10.09    
Number of employees terminated | event               2    
Net increase in share-based compensation as a result of stock awards modification | $           $ 3,100,000        
Non Employee Consultant                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Options granted (in shares)           125,779 109,887 265,517    
Weighted-average exercise price, granted (in dollars per share) | $ / shares           $ 15.67 $ 17.12 $ 20.05    
Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Award vesting period           4 years        
Awards vesting percentage           25.00%        
Exercise of vested stock options (in shares)           0 0 0    
Employee Stock Option | Key Employees                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Outstanding options (in shares)           7,103,801 7,103,801      
Employee Stock Option | Tranche Two                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Employee Stock Option | Tranche Three                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Employee Stock Option | Tranche Four                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Non Employee Stock Option | Minimum                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Award vesting period           1 year        
Non Employee Stock Option | Maximum                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Award vesting period           4 years        
Non Employee Stock Option | Tranche One                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Non Employee Stock Option | Tranche Two                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Non Employee Stock Option | Tranche Three                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Non Employee Stock Option | Tranche Four                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Non-Qualified Options | Key Employees                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Common stock granted (in shares)             3,400,000 4,703,801    
Restricted Stock Awards                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Award vesting period           4 years        
Restricted stock awarded (in shares)           8,994,729 2,365,000 508,303    
Fair value of restricted stock vested in period | $           $ 9,900,000 $ 1,500,000 $ 600,000    
Shares paid for tax withholding for share-based compensation (in shares)           441,537 45,142 16,623    
Shares paid for tax withholding for share-based compensation, cost | $           $ 1,600,000 $ 400,000 $ 200,000    
Treasury stock purchases (in shares)           533,427        
Treasury stock due to canceled RSA (in shares)           324,213 218,750 160,220    
Vesting triggering event, percent of average share price to grant date stock price           200.00%        
Restricted Stock Awards | Key Employees                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Restricted stock awarded (in shares)             1,000,000 400,000    
Restricted stock (in shares)           1,399,980 1,749,988      
Restricted Stock Awards | Chief Executive Officer                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of shares granted             500,000      
Restricted Stock Awards | Tranche One                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Restricted Stock Awards | Tranche Two                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Restricted Stock Awards | Tranche Three                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Restricted Stock Awards | Tranche Four                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Awards vesting percentage           25.00%        
Amended and Restated 2010 Stock Incentive Plan                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Additional shares authorized 5,000,000                  
2010 Stock Incentive Plan                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Maximum number of shares issuable under plan           29,374,756        
Number of shares available for future grants under the 2010 plan           5,148,848        
Plan Modification Due to Restructuring Plans                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of employees terminated | employee         13          
Net increase in share-based compensation as a result of stock awards modification | $               $ 1,100,000    
Plan Modification Due to Restructuring Plans | Senior Executive                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Extension of the exercise period for vested options before plan modification       60 days            
Net increase in share-based compensation as a result of stock awards modification | $             $ 5,600,000      
Extension of the exercise period for vested options, after the effective period of registration statement       60 days            
Plan Modification Due to Restructuring Plans | Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Extension of the exercise period for vested options before plan modification         60 days          
Extension of the exercise period for vested options after plan modification         60 days          
Net increase in share-based compensation as a result of stock awards modification | $             2,300,000      
Number of employees affected by modification of share-based awards | employee     39         13    
Extension of the exercise period for vested options, after the effective period of registration statement     60 days              
Plan Modification Due to Transition of CEO Role                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Net increase in share-based compensation as a result of stock awards modification | $             100,000 $ 1,500,000    
Plan Modification Due to Transition of CEO Role | Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Extension of the exercise period for vested options before plan modification         60 days          
Extension of the exercise period for vested options after plan modification         10 years          
Plan Modification Due to Retention Equity Awards Granted to COO                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Net increase in share-based compensation as a result of stock awards modification | $           $ 600,000 900,000      
Plan Modification Due to Modification of Award Terms Granted to COO                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Net increase in share-based compensation as a result of stock awards modification | $             $ 200,000      
Plan Modification Due to Modification of Award Terms Granted to COO | Employee Stock Option | Minimum                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Extension of the exercise period for vested options after plan modification             60 days      
Plan Modification Due to Modification of Award Terms Granted to COO | Employee Stock Option | Maximum                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Extension of the exercise period for vested options after plan modification             2 years      
Plan Modification Due to Cash Settlement of Awards                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Net increase in share-based compensation as a result of stock awards modification | $             $ 900,000      
Number of employees affected by modification of share-based awards | employee             3      
Two Thousand Fourteen Bonus Plan RSA [Member]                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Net increase in share-based compensation as a result of stock awards modification | $           $ 1,800,000        
Two Thousand Fourteen Bonus Plan RSA [Member] | Restricted Stock Awards                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Deferred Compensation Arrangement with Individual, Distributions Paid, Amount Per Share | $ / shares   $ 2.66                
Restricted Stock, Trading Price Per Share | $ / shares   $ 5.38             $ 2.72