Stock Awards - Summary of Restricted Stock Activity (Detail) (USD $)	6 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Jun. 30, 2011	Jun. 30, 2010
Shares Outstanding
Number of Shares, Early exercised	1,469,118	6,654,558	4,279,456	7,036,768
Restricted Stock [Member]
Shares Outstanding
Beginning balance	415,488	578,616	0
Number of Shares, Early exercised	360,852	263,970	453,243
Number of Shares, Vested	(185,640)	(573,352)	(37,755)
Shares repurchased and cancelled (shares)	12,084	34,168
Ending balance	578,616	235,066	415,488
Weighted-Average Grant Date Fair Value
Weighted-Average Grant Date Fair Value, Outstanding, Beginning Balance, usd per share	0.89	1.21	0
Weighted-Average Grant Date Fair Value, Early exercised, usd per share	1.29	2.38	0.86
Weighted-Average Grant Date Fair Value, Vested, usd per share	0.66	1.62	0.58
Weighted-Average Grant Date Fair Value, Repurchased, usd per share	0.74	1.42
Weighted-Average Grant Date Fair Value, Outstanding, Ending Balance, usd per share	1.21	1.49	0.89