Stock Awards - Summary of stock option activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011
Summary of stock option activity
Number of Shares, Outstanding, Beginning Balance		36,115,460	39,601,640
Number of Shares, Granted		2,339,523	7,695,730
Number of Shares, Exercised		(12,951,123)	(6,654,558)
Number of Shares, Forfeited		(2,104,486)	(4,527,352)
Number of Shares, Outstanding, Ending Balance	39,601,640	23,399,374	36,115,460
Number of Shares, Vested and expected to vest		22,304,397
Number of Shares, Vested and exercisable		9,333,628
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted-Average Exercise Price, Outstanding, Beginning Balance, usd per share		$ 5.05	$ 2.20
Weighted-Average Exercise Price, Granted, usd per share		$ 38.07	$ 15.03
Weighted-Average Exercise Price, Exercised, usd per share		$ 3.34	$ 0.76
Weighted-Average Exercise Price, Forfeited, usd per share		$ 7.66	$ 3.35
Weighted-Average Exercise Price, Outstanding, Ending Balance, usd per share	$ 2.20	$ 9.07	$ 5.05
Weighted-Average Exercise Price, Vested and expected to vest, usd per share		$ 8.71
Weighted-Average Exercise Price, Vested and exercisable, usd per share		$ 4.43
Weighted-Average Remaining Contractual Life		7 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest		7 years 8 months 23 days
Weighted-Average Remaining Contractual Term, Vested and exercisable		7 years 3 months 19 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 2,400	$ 446,054	$ 84,215	$ 7,500
Aggregate Intrinsic Value, Outstanding		1,097,746
Aggregate Intrinsic Value, Vested and expected to vest		1,054,997
Aggregate Intrinsic Value, Vested and exercisable		$ 481,448

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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