Short Term Borrowings and Credit Lines - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Nov. 01, 2011	May 31, 2013	May 31, 2012
Debt Instrument [Line Items]
Amounts outstanding under commercial paper program		$ 0	$ 0
Revolving credit facility, borrowing capacity	1,000,000,000
Revolving credit facility, optional maximum borrowing capacity	1,500,000,000.0
Revolving credit facility, optional extension period (in years)	1 year
Basis spread on variable rate, above LIBOR		0.56%
Revolving credit facility, fee		0.065%
Line of credit facility, amount outstanding		$ 0	$ 0
External Credit Rating, Standard & Poor's
Debt Instrument [Line Items]
Long-term senior unsecured debt rating		A+
External Credit Rating, Moody's
Debt Instrument [Line Items]
Long-term senior unsecured debt rating		A1
Before Extension
Debt Instrument [Line Items]
Revolving credit facility, maturity period	Nov. 01, 2016
After Extension | Maximum
Debt Instrument [Line Items]
Revolving credit facility, maturity period	Nov. 01, 2018
Sojitz America Accounts Payable
Debt Instrument [Line Items]
Accounts payable, due date period (in days)		60 days
Accounts payable, interest rate margin above LIBOR		0.75%