Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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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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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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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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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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Stock Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 07, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	2,500,000
Tax benefits recorded on stock based compensation	$ 70.6	$ 61.6	$ 37.3
Aggregate intrinsic value of options exercisable	$ 569.0
Weighted average remaining contractual term of options exercisable (in years)	4 years 9 months 18 days
Weighted-average remaining contractual life for options outstanding (in years)	5 years 3 months 18 days
Shares, granted (in shares)	171,000	232,000	107,000
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, granted (in shares)	0		0
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized to issue grants (in shares)				16,750,000