Consolidated Statements Of Redeemable Convertible Preferred Stock And Stockholders' Equity (Deficit) (Parenthetical) (USD $)
In Thousands, except Per Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Initial Public Offering [Member]
 
Stock issuance costs $ 2,915
Issuance price of common stock $ 19.00
Secondary Offering [Member]
 
Stock issuance costs $ 540
Issuance price of common stock $ 20.49