Computation of Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 28, 2015		Feb. 28, 2014		Feb. 28, 2015		Feb. 28, 2014
Basic earnings per common share:
Net earnings allocable to common shares	$ 579	[1]	$ 377	[1]	$ 1,799	[1]	$ 1,365	[1]
Weighted-average common shares	283		303		284		312
Basic earnings per common share	$ 2.05		$ 1.24		$ 6.34		$ 4.38
Diluted earnings per common share:
Net earnings allocable to common shares	$ 579	[1]	$ 377	[1]	$ 1,799	[1]	$ 1,365	[1]
Weighted-average common shares	283		303		284		312
Dilutive effect of share-based awards	4		4		4		3
Weighted-average diluted shares	287		307		288		315
Diluted earnings per common share	$ 2.01		$ 1.23		$ 6.25		$ 4.34
Anti-dilutive options excluded from diluted earnings per common share	2.0		0.5		2.1		4.3

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