Redeemable Convertible Preferred Shares - Series E Convertible Redeemable Preferred Shares - Additional Information (Detail)
 3 Months Ended 12 Months Ended
Jun. 24, 2014
USD ($)
$ / shares
shares
Apr. 24, 2014
USD ($)
item
shares
Mar. 05, 2014
USD ($)
$ / shares
shares
Jun. 04, 2014
$ / shares
shares
Dec. 31, 2015
USD ($)
$ / shares
shares
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Aug. 31, 2013
USD ($)
Conversion of Stock [Line Items]                
Incremental benefits         $ 0      
Fair value of warrant liability           $ (8,054,000) $ (1,531,000)  
First Two Investors [Member]                
Conversion of Stock [Line Items]                
Total consideration   $ 100,000,000            
Third Investor [Member]                
Conversion of Stock [Line Items]                
Total consideration   10,000,000            
Unvested restricted stock [Member]                
Conversion of Stock [Line Items]                
Number of shares imposed transfer restrictions | shares         3,394,564      
Unvested options [Member]                
Conversion of Stock [Line Items]                
Number of shares imposed transfer restrictions | shares         180,000      
Vested options [Member]                
Conversion of Stock [Line Items]                
Number of shares imposed transfer restrictions | shares         180,000      
Common shares [Member]                
Conversion of Stock [Line Items]                
Shares subscribed | shares         39,934,162      
Subscription Rights [Member]                
Conversion of Stock [Line Items]                
Initial fair value of subscription rights   28,208,000            
Fair value of subscription rights   $ 29,223,000            
Series E Preferred Shares [Member]                
Conversion of Stock [Line Items]                
Total consideration from issuance of Series E preferred shares and warrants     $ 200,000,000          
Preferred stock, shares issued | shares     70,975,491          
Preferred stock issued price | $ / shares     $ 2.82          
Warrants to purchase preferred shares | shares     3,406,824          
Warrants exercise price | $ / shares     $ 2.82          
Percentage of issue price         100.00%      
Converted into common share | shares         129,166,667      
Interest rate for delayed period         15.00%      
Initial conversion price | $ / shares $ 2.82              
Adjusted conversion price | $ / shares $ 2.4              
Initial fair value of warrants         $ 2,819,000      
Fair value of warrant liability $ 6,381,000              
Beneficial conversion feature         27,396,000      
Shares held by investors | shares 110,014,440              
Unamortized beneficial conversion feature for preferred shares anti-diluted         $ 49,346,000      
Series E Preferred Shares [Member] | Convertible Redeemable Preferred Shares [Member]                
Conversion of Stock [Line Items]                
Converted into common share | shares         1      
Series E Preferred Shares [Member] | Subscription Rights [Member]                
Conversion of Stock [Line Items]                
Warrants exercise price | $ / shares         $ 2.82      
Right to purchase additional number of preferred shares by investor | shares         35,487,746      
Series E Tranche 1 Investor [Member]                
Conversion of Stock [Line Items]                
Warrants to purchase preferred shares | shares     17,743,873          
Warrants exercise price | $ / shares     $ 2.82          
Series E Tranche 1 Investor [Member] | Subscription Rights [Member]                
Conversion of Stock [Line Items]                
Shares subscribed | shares       35,487,746        
Preferred stock, price per share repurchased | $ / shares       $ 2.28        
Series E Tranche 1 Preferred Shares [Member]                
Conversion of Stock [Line Items]                
Amount of beneficial conversion feature         $ 52,377,000      
Common stock fair value per share | $ / shares         $ 3.05      
Initial conversion price | $ / shares         2.82      
Adjusted conversion price | $ / shares         $ 2.31      
Series E Tranche 1 Preferred Shares [Member] | Convertible Redeemable Preferred Shares [Member]                
Conversion of Stock [Line Items]                
Amount of beneficial conversion feature         $ (53,486,000)      
Series E Tranche 1 Investor Options [Member]                
Conversion of Stock [Line Items]                
Valuation based on subscription price     $ 30,000,000,000   $ 10,000,000,000     $ 10,000,000,000
Percentage of approval for transfer of preferred shares         75.00%      
Valuation of transfer restriction         $ 43,300,000      
Percentage increase in valuation         200.00%      
Series E Warrants [Member]                
Conversion of Stock [Line Items]                
Initial fair value of warrants         $ 6,477,000      
Preferred stock, price per share repurchased | $ / shares       $ 2.82        
Fair value of warrant liability              
Series E Tranche 2 Investor [Member]                
Conversion of Stock [Line Items]                
Number of investors | item   2            
Number of investors exercised the Subscription Rights | item   3            
Series E Tranche 2 Preferred Shares [Member]                
Conversion of Stock [Line Items]                
Shares subscribed | shares   39,037,382            
Total consideration   $ 110,000            
Fair value of warrant liability   29,223,000            
Series E Tranche 2 Preferred Shares [Member] | First Two Investors [Member]                
Conversion of Stock [Line Items]                
Total consideration   100,000,000            
Beneficial conversion feature   1,109,000            
Series E Tranche 2 Preferred Shares [Member] | Third Investor [Member]                
Conversion of Stock [Line Items]                
Total consideration   10,000,000            
Beneficial conversion feature   $ 0