Employee Incentive and Retirement Plans - Options Activity Under Option Plan (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balances, beginning balance, Number of Shares \| shares	48,208,911
Options Granted, Number of Shares \| shares	4,547,230
Options Exercised, Number of Shares \| shares	(3,822,799)
Options Forfeited/Expired, Number of Shares \| shares	(478,682)
Balances, ending balance, Number of Shares \| shares	48,454,660
Vested and expected to vest, Number of Shares \| shares	48,091,745
Exercisable, Number of Shares \| shares	26,444,648
Balances, beginning balance, Weighted Average Exercise Price Per Share \| $ / shares	$ 3.60
Options Granted, Weighted Average Exercise Price Per Share \| $ / shares	8.48
Options Exercised, Weighted Average Exercise Price Per Share \| $ / shares	1.26
Options Forfeited/Expired, Weighted Average Exercise Price Per Share \| $ / shares	6.97
Balances, ending balance, Weighted Average Exercise Price Per Share \| $ / shares	4.21
Vested and expected to vest, Weighted Average Exercise Price Per Share \| $ / shares	4.20
Exercisable, Weighted Average Exercise Per Share \| $ / shares	$ 2.36
Outstanding, Weighted Average Remaining Contractual Life	7 years 1 month 5 days
Vested and expected to vest, Weighted Average Remaining Contractual Life	7 years 1 month
Exercisable, Weighted Average Remaining Contractual Life	6 years 2 months
Outstanding, Aggregate Intrinsic Value \| $	$ 221,874
Vested and expected to vest, Aggregate Intrinsic Value \| $	220,963
Exercisable, Aggregate Intrinsic Value \| $	$ 163,676
Share price ($ per share) \| $ / shares	$ 8.30
Employee Stock Option - Vested
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Granted, Number of Shares \| shares	265,987
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase period	6 months

Share-based Compensation Arrangement By Share-based Payment Award, Offering Period

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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.

+ References

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-Name Accounting Standards Codification
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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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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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

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No definition available.

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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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

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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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Price of a single share of a number of saleable stocks of a company.

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

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