Income Taxes - Income before Income Taxes (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Aug. 31, 2013	Aug. 31, 2012	May 31, 2013
Income Tax Disclosure [Abstract]
Effective tax rate on continuing operations (percent)	25.00%	26.90%
Total gross unrecognized tax benefits, excluding related interest and penalties	$ 491		$ 447
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	315
Increase in liability for payment of interest and penalties	10
Accrued interest and penalties related to uncertain tax positions (excluding federal benefit)	122
Estimated decrease in total gross unrecognized tax benefits as a result of resolutions of global tax examinations and expiration of applicable statutes of limitations	$ 25

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties.

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