Stock Option Exercises and Restricted Stock Vesting (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Proceeds from stock option exercises	$ 131.5	$ 124.4
Aggregate intrinsic value	107.7	89.0
Tax benefit realized upon exercise/vesting	38.7	32.6
Number of shares exercised	2.8	3.5
Restricted Stock [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Fair value of shares vested	92.3	54.0
Tax benefit realized upon exercise/vesting	31.6	19.2
Number of shares vested	1.2	1.1
Restricted Stock [Member] | Non Market Performance Based Vesting Condition [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Fair value of shares vested	38.0	25.5
Tax benefit realized upon exercise/vesting	$ 14.6	$ 9.7
Number of shares vested	0.5	0.5