Share-Based Awards - Summary of Option Award (Detail) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Number of Shares Subject to Existing Options
Beginning Balance (in shares) \| shares	29,634,296
Granted (in shares) \| shares	5,037,920
Exercised (in shares) \| shares	(11,779,104)
Forfeited or cancelled (in shares) \| shares	(916,931)
Ending Balance (in shares) \| shares	21,976,181	29,634,296
Vested and exercisable ending balance (in shares) \| shares	10,490,317
Weighted- Average Exercise Price Per Share
Beginning Balance (usd per share) \| $ / shares	$ 35.95
Granted (usd per share) \| $ / shares	50.76
Exercised (usd per share) \| $ / shares	31.52
Forfeited or cancelled (usd per share) \| $ / shares	42.00
Ending Balance (usd per share) \| $ / shares	41.47	$ 35.95
Vested and exercisable (usd per share) \| $ / shares	$ 37.59
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-Average Remaining Contractual Life, Outstanding	7 years 1 month 28 days	6 years 3 months 10 days
Weighted-Average Remaining Contractual Life, Vested and exercisable	5 years 6 months 21 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Aggregate Intrinsic Value, Outstanding \| $	$ 1,321,219	$ 331,107
Aggregate Intrinsic Value Vested, and exercisable \| $	$ 671,352

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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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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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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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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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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 exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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