Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	May 31, 2012
Income Taxes [Line Items]
Effective tax rate (percent)	27.50%	24.30%
Total gross unrecognized tax benefits, excluding related interest and penalties	$ 310		$ 285
Total gross unrecognized tax benefits, excluding related interest and penalties, amount which would affect the Company's effective tax rate if recognized in future periods	168		150
Increase in liability for payment of interest and penalties	8
Accrued interest and penalties related to uncertain tax positions (excluding federal benefit)	116
Estimated decrease in total gross unrecognized tax benefits as a result of resolutions of global tax examinations and expiration of applicable statutes of limitations	$ 63
Internal Revenue Service (IRS) | Period 1
Income Taxes [Line Items]
Years under examination	2011
Internal Revenue Service (IRS) | Period 2
Income Taxes [Line Items]
Years under examination	2012