Summary of Option Activity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning Balance, Options			8.8
Granted, Options	0	0	1.1	1.6
Exercised, Options			(1.0)
Cancelled, Options			(0.1)
Ending Balance, Options	8.8		8.8
Exercisable at September 30, 2014, Options	4.5		4.5
Beginning Balance, Weighted-Average Exercise Price			$ 39.47
Granted, Weighted-Average Exercise Price			$ 69.60
Exercised, Weighted-Average Exercise Price			$ 24.23
Cancelled, Weighted-Average Exercise Price			$ 55.32
Ending Balance, Weighted-Average Exercise Price	$ 44.90		$ 44.90
Exercisable at September 30, 2014, Weighted-Average Exercise Price	$ 29.79		$ 29.79
Outstanding at September 31, 2014, Weighted-Average Remaining Contractual Term, years			6 years 3 months 18 days
Exercisable at September 31, 2014, Weighted-Average Remaining Contractual Term, years			4 years 3 months 18 days
Outstanding at September 30, 2014, Aggregate Intrinsic Value	$ 222.1		$ 222.1
Exercisable at September 30, 2014, Aggregate Intrinsic Value	$ 182.5		$ 182.5