Computation of Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2011		Nov. 30, 2010		Nov. 30, 2011		Nov. 30, 2010
Basic earnings per common share:
Net earnings allocable to common shares	$ 495	[1]	$ 282	[1]	$ 959	[1]	$ 661	[1]
Weighted-average common shares	315		314		316		314
Basic earnings per common share	$ 1.57		$ 0.90		$ 3.04		$ 2.11
Diluted earnings per common share:
Net earnings allocable to common shares	$ 495	[1]	$ 282	[1]	$ 959	[1]	$ 661	[1]
Weighted-average common shares	315		314		316		314
Dilutive effect of share-based awards	1		2		1		2
Weighted-average diluted shares	316		316		317		316
Diluted earnings per common share	$ 1.57		$ 0.89		$ 3.02		$ 2.09
Anti-dilutive options excluded from diluted earnings per common share	14.2		11.2		13.7		11.3

[1]  Net earnings available to participating securities were immaterial in all periods presented.