v2.4.0.8
Redeemable Convertible Preferred Stock and Shareholders' Equity (Deficit) - Summary of Redeemable Convertible Preferred Stock (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
9 Months Ended 12 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Dec. 31, 2012
Dec. 31, 2011
Temporary Equity [Line Items]        
Accretion of dividends $ 18,391 $ 16,291 $ 21,994 $ 13,868
Series A Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 1,358 802 802 802
Issuance of shares           
Accretion of dividends 52   556   
Stock issuance costs           
Conversion to common stock (1,410)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      1,358 802
Beginning Balance, Shares 705,400 705,400 705,400 705,400
Issuance of shares, Shares           
Conversion to common stock, Shares (705,400)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   705,400 705,400
Series B Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 669 639 639 609
Issuance of shares           
Accretion of dividends 19   30 30
Stock issuance costs           
Conversion to common stock (688)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      669 639
Beginning Balance, Shares 694,000 694,000 694,000 694,000
Issuance of shares, Shares           
Conversion to common stock, Shares (694,000)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   694,000 694,000
Series B-1 Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 1,360 1,300 1,300 1,240
Issuance of shares           
Accretion of dividends 37   60 60
Stock issuance costs           
Conversion to common stock (1,397)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      1,360 1,300
Beginning Balance, Shares 1,212,360 1,212,360 1,212,360 1,212,360
Issuance of shares, Shares           
Conversion to common stock, Shares (1,212,360)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   1,212,360 1,212,360
Series C Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 7,134 6,729 6,729 6,346
Issuance of shares           
Accretion of dividends 266   405 383
Stock issuance costs           
Conversion to common stock (7,400)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      7,134 6,729
Beginning Balance, Shares 4,546,360 4,546,360 4,546,360 4,546,360
Issuance of shares, Shares           
Conversion to common stock, Shares (4,546,360)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   4,546,360 4,546,360
Series C-1 Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 34,201 32,264 32,264 30,436
Issuance of shares           
Accretion of dividends 1,272   1,937 1,828
Stock issuance costs           
Conversion to common stock (35,473)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      34,201 32,264
Beginning Balance, Shares 15,934,528 15,934,528 15,934,528 15,934,528
Issuance of shares, Shares           
Conversion to common stock, Shares (15,934,528)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   15,934,528 15,934,528
Series C-2 Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 44,512 41,987 41,987 39,605
Issuance of shares           
Accretion of dividends 1,660   2,525 2,382
Stock issuance costs           
Conversion to common stock (46,172)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      44,512 41,987
Beginning Balance, Shares 18,617,020 18,617,020 18,617,020 18,617,020
Issuance of shares, Shares           
Conversion to common stock, Shares (18,617,020)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   18,617,020 18,617,020
Series C-3 Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 29,770 28,082 28,082 26,489
Issuance of shares           
Accretion of dividends 1,103   1,688 1,593
Stock issuance costs           
Conversion to common stock (30,873)      
Settlement of fractional shares upon conversion to common stock         
Ending Balance      29,770 28,082
Beginning Balance, Shares 13,297,872 13,297,872 13,297,872 13,297,872
Issuance of shares, Shares         
Conversion to common stock, Shares (13,297,872)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   13,297,872 13,297,872
Series D Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 76,252 71,924 71,924 39,019
Issuance of shares         28,942
Accretion of dividends 2,827   4,328 3,971
Stock issuance costs         (8)
Conversion to common stock (79,078)      
Settlement of fractional shares upon conversion to common stock (1)      
Ending Balance      76,252 71,924
Beginning Balance, Shares 19,803,685 19,803,685 19,803,685 11,240,794
Issuance of shares, Shares        8,562,891
Conversion to common stock, Shares (19,803,685)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   19,803,685 19,803,685
Series E Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance 211,403 117,954 117,954   
Issuance of shares      83,000 117,000
Accretion of dividends 7,931   10,465 3,621
Stock issuance costs      (16) (2,667)
Conversion to common stock (219,332)      
Settlement of fractional shares upon conversion to common stock (2)      
Ending Balance      211,403 117,954
Beginning Balance, Shares 38,095,239 22,285,716 22,285,716  
Issuance of shares, Shares      15,809,523 22,285,716
Conversion to common stock, Shares (38,095,239)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0   38,095,239 22,285,716
Series F Redeemable Convertible Preferred Stock [Member]
       
Temporary Equity [Line Items]        
Beginning Balance         
Issuance of shares 150,000      
Accretion of dividends 3,224      
Stock issuance costs (3,148)      
Conversion to common stock (150,075)      
Settlement of fractional shares upon conversion to common stock (1)      
Ending Balance $ 0      
Beginning Balance, Shares         
Issuance of shares, Shares 19,047,619      
Conversion to common stock, Shares (19,047,619)      
Settlement of fractional shares upon conversion to common stock, Shares         
Ending Balance, Shares 0