Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	May 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities with maturity dates within one year from purchase date	$ 1,674		$ 2,287
Available-for-sale securities with maturity dates over one year and less than five years from purchase date	602		635
Interest income related to cash and equivalents and short-term investments	1	1
Fair value of long term debt	$ 1,177		$ 1,154