Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012
Fair Value Disclosures [Abstract]
Available-for-sale securities with maturity dates within one year from purchase date	$ 2,287	$ 2,229
Available-for-sale securities with maturity dates over one year and less than five years from purchase date	635	399
Interest income related to cash and equivalents and short-term investments	$ 5	$ 4	$ 6