Computation of Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Aug. 31, 2013		Aug. 31, 2012
Basic earnings per common share:
Net earnings allocable to common shares	$ 489	[1]	$ 458	[1]
Weighted-average common shares	316		315
Basic earnings per common share	$ 1.54		$ 1.46
Diluted earnings per common share:
Net earnings allocable to common shares	$ 489	[1]	$ 458	[1]
Weighted-average common shares	316		315
Dilutive effect of share-based awards	3		1
Weighted-average diluted shares	319		316
Diluted earnings per common share	$ 1.53		$ 1.45
Anti-dilutive options excluded from diluted earnings per common share	9.8		13.9

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