Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	May. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities with maturity dates within one year from purchase date	$ 1,905,000,000
Available-for-sale securities with maturity dates over one year and less than five years from purchase date	257,000,000
Interest income	2,000,000	$ 1,000,000
Fair value of long term debt	1,130,000,000		$ 1,160,000,000
Fair value transfers between fair value hierarchy levels	0
Assets, fair value disclosure, nonrecurring			0
Liabilities, fair value disclosure, nonrecurring	0		0
Prepaid Expenses and Other Current Assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Outstanding receivables	200,000,000		150,000,000
Foreign exchange forwards and options | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liability, fair value of collateral	$ 0		$ 0