Earnings Per Common Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2011
Basic and diluted earnings per common share
Income available to common stockholders	$ 81.7	$ 109.5	$ 124.6	$ 72.0	$ 103.0	$ 104.8	$ 162.7	$ 74.5	$ 387.8	$ 445.0	$ 559.5
Class A Common Stock [Member]
Weighted average common shares outstanding – basic:
Weighted average common shares outstanding - basic									158,658,000	180,724,000	187,224,000
Weighted average common shares outstanding – diluted:
Weighted average common shares outstanding - basic									158,658,000	180,724,000	187,224,000
Stock-based awards, primarily stock options									8,117,000	4,341,000	2,855,000
Weighted average common shares outstanding - diluted									190,307,000	208,655,000	213,765,000
Earnings per common share – basic:
Earnings per common share - basic (in dollars per share)	$ 0.45	$ 0.61	$ 0.71	$ 0.39	$ 0.53	$ 0.53	$ 0.78	$ 0.36	$ 2.15	$ 2.20	$ 2.68
Earnings per common share – diluted:
Earnings per common share - diluted (in dollars per share)	$ 0.43	$ 0.58	$ 0.67	$ 0.38	$ 0.51	$ 0.52	$ 0.76	$ 0.35	$ 2.04	$ 2.13	$ 2.62
Earnings Per Common Share (Textual)
Antidilutive shares not included in computation of earnings per common share									300,000	8,900,000	20,700,000
Class B Convertible Common Stock [Member]
Weighted average common shares outstanding – basic:
Weighted average common shares outstanding - basic									23,532,000	23,590,000	23,686,000
Weighted average common shares outstanding – diluted:
Weighted average common shares outstanding - basic									23,532,000	23,590,000	23,686,000
Weighted average common shares outstanding - diluted									23,532,000	23,590,000	23,686,000
Earnings per common share – basic:
Earnings per common share - basic (in dollars per share)	$ 0.41	$ 0.55	$ 0.64	$ 0.36	$ 0.48	$ 0.48	$ 0.71	$ 0.32	$ 1.96	$ 2.00	$ 2.44
Earnings per common share – diluted:
Earnings per common share - diluted (in dollars per share)	$ 0.39	$ 0.53	$ 0.62	$ 0.35	$ 0.47	$ 0.47	$ 0.70	$ 0.32	$ 1.87	$ 1.96	$ 2.40