Stock Option Exercises and Restricted Stock Vesting (Detail) - USD ($) shares in Millions, $ in Millions	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Proceeds from stock option exercises	$ 35.3	$ 33.4
Aggregate intrinsic value	52.2	21.0
Tax benefit realized upon exercise/vesting	$ 18.3	$ 7.4
Number of shares exercised	0.8	0.6
Restricted Stock [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Fair value of shares vested	$ 107.9	$ 90.6
Tax benefit realized upon exercise/vesting	$ 34.1	$ 29.6
Number of shares vested	1.0	1.0
Vesting of Performance Based Restricted Stock [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Fair value of shares vested	$ 19.5	$ 23.6
Tax benefit realized upon exercise/vesting	$ 6.9	$ 8.4
Number of shares vested	0.2	0.2

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

+ References

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-Publisher FASB
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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

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