Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2013	Nov. 30, 2012	May 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities with maturity dates within one year from purchase date	$ 2,280		$ 2,280		$ 2,229
Available-for-sale securities with maturity dates over one year and less than five years from purchase date	821		821		399
Interest income related to cash and equivalents and short-term investments	4	6	6	14
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of long term debt	1,105		1,105		1,219
Reverse Repurchase Agreements Receivables	$ 100		$ 100