Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock options, granted (in shares) \| shares	0.1
Employee stock options, weighted average grant date fair value (in usd per share) \| $ / shares	$ 60.66
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options, shares granted (in shares) \| shares	0.5
Other than options, weighted average grant date fair value (in usd per share) \| $ / shares	$ 278.92
Award vesting period (in years)	4 years
Unrecognized compensation expense \| $	$ 192
Weighted average period to recognize expense	2 years 6 months
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	4 years
Unrecognized compensation expense \| $	$ 8
Weighted average period to recognize expense	2 years 4 months 24 days
Performance Based Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options, shares granted (in shares) \| shares	0.1
Other than options, weighted average grant date fair value (in usd per share) \| $ / shares	$ 273.81
Award vesting period (in years)	3 years
Unrecognized compensation expense \| $	$ 34
Weighted average period to recognize expense	2 years

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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-Publisher FASB
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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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