Summary of Option Activity (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Options			8.2
Granted, Options	1.6	1.5	1.6	1.5
Exercised, Options			(0.6)
Cancelled, Options			(0.1)
Ending Balance, Options	9.1		9.1
Exercisable at June 30, 2013, Options	4.9		4.9
Beginning Balance, Weighted-Average Exercise Price			$ 32.81
Granted, Weighted-Average Exercise Price			$ 61.88
Exercised, Weighted-Average Exercise Price			$ 20.27
Cancelled, Weighted-Average Exercise Price			$ 45.93
Ending Balance, Weighted-Average Exercise Price	$ 38.62		$ 38.62
Exercisable at June 30, 2013, Weighted-Average Exercise Price	$ 25.86		$ 25.86
Outstanding at June 30, 2013, Weighted-Average Remaining Contractual Term, years			6 years 7 months 6 days
Exercisable at June 30, 2013, Weighted-Average Remaining Contractual Term, years			4 years 7 months 6 days
Outstanding at June 30, 2013, Aggregate Intrinsic Value	$ 211.4		$ 211.4
Exercisable at June 30, 2013, Aggregate Intrinsic Value	$ 175.3		$ 175.3