Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options, Outstanding at beginning of year	8,500
Options, Granted	2,800
Options, Exercised	(500)
Options, Forfeited	(100)
Options, Outstanding at December 31, 2019	10,700
Options, Exercisable at December 31, 2019	5,900
Weighted average exercise price, Outstanding at beginning of year	$ 95.26
Weighted average exercise price, Granted	114.73
Weighted average exercise price, Exercised	74.74
Weighted average exercise price, Forfeited	90.11
Weighted average exercise price, Outstanding at December 31, 2019	101.57
Weighted average exercise price, Exercisable at December 31, 2019	$ 94.75
Aggregate intrinsic value, Outstanding	$ 122.4	$ 101.2
Aggregate intrinsic value, Exercisable as of December 31, 2019	$ 103.0

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

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