Share-Based Awards and Options - Stock Option Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		12 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	May 31, 2013	Feb. 28, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	1,765,000
Granted (in shares)	0	0
Forfeited (in shares)	(64,000)
Exercised (in shares)	(911,000)
Outstanding, end of period (in shares)	790,000		1,765,000
Options vested and exercisable (in shares)	732,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, Weighted Average Exercise Price, beginning of period (in dollars per share)	$ 35
Granted, Weighted Average Exercise Price (in dollars per share)	$ 0
Forfeited, Weighted Average Exercise Price (in dollars per share)	$ 39
Exercised, Weighted Average Exercise Price (in dollars per share)	$ 30
Outstanding, Weighted Average Exercise Price, end of period (in dollars per share)	$ 40		$ 35
Options vested and exercisable, Weighted Average Exercise Price (in dollars per share)	$ 41
Outstanding, Weighted Average Remaining Contractual Term	4 years 1 month 6 days		3 years 6 months
Options vested and exercisable, Weighted Average Remaining Contractual Term	3 years 10 months 24 days
Outstanding, Aggregate Intrinsic Value	$ 23.9			$ 23.2
Options vested and exercisable, Aggregate Intrinsic Value	$ 21.3