v2.4.0.6
Summary of stock option activity (Detail) (USD $)
 6 Months Ended 9 Months Ended 12 Months Ended
Dec. 31, 2011
Sep. 30, 2012
Jun. 30, 2011
Jun. 30, 2010
Jun. 30, 2009
Summary of stock option activity          
Number of Shares, Outstanding, Beginning Balance 26,326,394 39,601,640 16,520,984 19,164,000 16,333,664
Number of Shares, Granted 17,055,120 7,085,680 15,402,456 4,684,000 4,160,000
Number of Shares, Exercised (1,469,118) (5,523,840) (4,279,456) (7,036,768) (348,328)
Number of Shares, Forfeited (2,310,756) (3,543,871) (867,590) (290,248) (981,336)
Number of shares, Cancelled   (340,167) (450,000)    
Number of Shares, Outstanding, Ending Balance 39,601,640 37,279,442 26,326,394 16,520,984 19,164,000
Weighted-Average Exercise Price, Outstanding, Beginning Balance $ 1.40 $ 2.20 $ 0.34 $ 0.07 $ 0.03
Number of Shares, Vested and expected to vest 38,723,419 36,593,833 26,025,366 16,175,929 18,842,329
Weighted-Average Exercise Price, Granted $ 3.29 $ 13.48 $ 2.15 $ 1.00 $ 0.21
Number of Shares, Vested and exercisable 10,123,858 11,607,655 8,628,975 7,895,777 10,723,479
Weighted-Average Exercise Price, Exercised $ 1.45 $ 0.61 $ 0.25 $ 0.03 $ 0.02
Weighted-Average Exercise Price, Forfeited $ 1.61 $ 3.22 $ 0.87 $ 0.41 $ 0.05
Weighted-Average Exercise Price Cancelled   $ 1.90 $ 0.18    
Weighted-Average Exercise Price, Outstanding, Ending Balance $ 2.20 $ 4.48 $ 1.40 $ 0.34 $ 0.07
Weighted-Average Exercise Price, Vested and expected to vest $ 2.17 $ 4.43 $ 1.39 $ 0.33 $ 0.06
Weighted-Average Exercise Price, Vested and exercisable $ 0.57 $ 1.77 $ 0.35 $ 0.07 $ 0.03
Weighted-Average Remaining Contractual Life (Years)   8 years 6 months 4 days      
Weighted-Average Remaining Contractual Term, Vested and expected to vest 8 years 7 months 10 days 8 years 6 months 8 years 4 months 13 days 7 years 8 months 19 days 7 years 9 months 4 days
Weighted-Average Remaining Contractual Term, Vested and exercisable 6 years 6 months 7 days 7 years 6 months 29 days 6 years 6 months 11 days 6 years 7 months 17 days 7 years 22 days
Aggregate Intrinsic Value, Outstanding   $ 1,274,895,101      
Aggregate Intrinsic Value, Vested and expected to vest 109,458,847 1,253,278,350 31,601,963 14,458,066 4,079,780
Aggregate Intrinsic Value, Vested and exercisable $ 44,821,224 $ 428,488,416 $ 19,421,343 $ 9,051,521 $ 2,748,003