Income Taxes - Income before Income Taxes (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	May 31, 2014
Income Tax Disclosure [Abstract]
Effective tax rate on continuing operations (percent)	21.70%	25.00%
Total gross unrecognized tax benefits, excluding related interest and penalties	$ 473		$ 506
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	253
Increase in liability for payment of interest and penalties	7
Accrued interest and penalties related to uncertain tax positions (excluding federal benefit)	160		167
Estimated decrease in total gross unrecognized tax benefits as a result of resolutions of global tax examinations and expiration of applicable statutes of limitations	$ 71