Short Term Borrowings and Credit Lines - Additional Information (Detail) - USD ($)	12 Months Ended
	May. 31, 2015	May. 31, 2014	Nov. 01, 2011
Short-term Debt [Line Items]
Amounts outstanding under commercial paper program	$ 0	$ 0
Line of credit facility, amount outstanding		$ 0
Interest Bearing Accounts Payable | 60-day London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Basis spread on variable rate, above LIBOR	0.75%
Sojitz America | Interest Bearing Accounts Payable
Short-term Debt [Line Items]
Accounts payable, due date period (in days)	60 days
Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, borrowing capacity			$ 1,000,000,000
Revolving credit facility, optional maximum borrowing capacity			$ 1,500,000,000.0
Revolving credit facility, fee	0.055%
Line of credit facility, amount outstanding	$ 0
Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Basis spread on variable rate, above LIBOR	0.445%