Debt and Receivables Securitization - Additional Information (Detail) (USD $)	3 Months Ended
	Aug. 31, 2013
Worthington Nitin Cylinders Limited
Debt And Receivables Securitization [Line Items]
Maximum borrowing capacity	$ 9,500,000
Maturity date	2013-11
Borrowings outstanding	4,187,000
Applicable variable rate	2.25%
Unsecured Revolving Credit Facility
Debt And Receivables Securitization [Line Items]
Maximum borrowing capacity	425,000,000
Maturity date	2017-05
Borrowings outstanding	18,000,000
Applicable variable rate	1.23%
Line of Credit
Debt And Receivables Securitization [Line Items]
Remaining borrowing capacity	395,268,000
Line of Credit | Maximum
Debt And Receivables Securitization [Line Items]
Debt maturity period	1 year
Accounts Receivable Facilities
Debt And Receivables Securitization [Line Items]
Maximum borrowing capacity	100,000,000
Maturity date	2015-01
Borrowings outstanding	40,000,000
Number of days past due trade accounts receivables are ineligible for securitization	90
Financial Stand-By Letters Of Credit
Debt And Receivables Securitization [Line Items]
Outstanding stand-by letters of credit amount for third-party beneficiaries	$ 11,732,000