Computation of Earnings Per Share (Details) (USD $) In Millions, except Per Share data	3 Months Ended																12 Months Ended
	May 31, 2011		Feb. 28, 2011		Nov. 30, 2010		Aug. 31, 2010		May 31, 2010		Feb. 28, 2010		Nov. 30, 2009		Aug. 31, 2009		May 31, 2011		May 31, 2010		May 31, 2009
Basic earnings per common share:
Net earnings allocable to common shares																	$ 1,449	[1]	$ 1,182	[1]	$ 97	[1]
Weighted-average common shares																	315		312		311
Basic earnings per common share	$ 1.76	[2]	$ 0.73	[2]	$ 0.90	[2]	$ 1.21	[2]	$ 1.34		$ 0.76		$ 1.10		$ 0.58		$ 4.61		$ 3.78		$ 0.31
Diluted earnings per common share:
Net earnings allocable to common shares																	$ 1,449	[1]	$ 1,182	[1]	$ 97	[1]
Weighted-average common shares																	315		312		311
Dilutive effect of share-based awards																	2		2		1
Weighted-average diluted shares																	317		314		312
Diluted earnings per common share	$ 1.75		$ 0.73		$ 0.89		$ 1.20		$ 1.33	[2]	$ 0.76	[2]	$ 1.10	[2]	$ 0.58	[2]	$ 4.57		$ 3.76		$ 0.31
Anti-dilutive options excluded from diluted earnings per common share																	9.3		11.5		12.6

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

[2] The sum of the quarterly earnings per share may not equal annual amounts due to differences in the weighted-average number of shares outstanding during the respective period.