Redeemable Convertible Preferred Stock (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
0 Months Ended 12 Months Ended 0 Months Ended
Nov. 23, 2011
Nov. 23, 2011
Common stock
Dec. 31, 2011
Series E
Nov. 23, 2011
Conversion of Preferred Stock Series A
Common stock
Nov. 23, 2011
Conversion of Preferred Stock Series A
Series A
Nov. 23, 2011
Conversion of Preferred Stock Series B
Common stock
Nov. 23, 2011
Conversion of Preferred Stock Series B
Series B
Nov. 23, 2011
Conversion of Preferred Stock Series C
Common stock
Nov. 23, 2011
Conversion of Preferred Stock Series C
Series C
Nov. 23, 2011
Conversion of Preferred Stock Series D
Common stock
Nov. 23, 2011
Conversion of Preferred Stock Series D
Series D
Nov. 23, 2011
Conversion of Preferred Stock Series E
Common stock
Nov. 23, 2011
Conversion of Preferred Stock Series E
Series E
Conversion of Stock [Line Items]                          
Preferred shares converted (in shares) 58,461,447       8,399,831   22,780,964   14,686,698   6,575,832   6,018,122
Conversion of stock, common shares issued (in shares)   29,230,708   4,199,912   11,390,477   7,343,345   3,287,915   3,009,059  
Series E stock issued during period (in shares)     6,018,122                    
Issuance price of preferred stock Series E (in usd per share)     $ 4.15                    
Proceeds from issuance of Series E preferred stock     $ 24,900