Debt and Receivables Securitization - Additional Information (Detail) (USD $)					12 Months Ended	1 Months Ended						1 Months Ended							12 Months Ended			12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2012 Cash Flow Hedges Interest Rate Contracts	May 31, 2012 Cash Flow Hedges Interest Rate Contracts Six-month LIBOR rate	May 31, 2012 2014 Notes	Apr. 13, 2010 6.50% Unsecured Senior Notes due April 15, 2020	Apr. 27, 2012 Term Loan maturing May 1, 2019	Dec. 29, 2011 Industrial revenue bonds due March 2013	May 31, 2012 Industrial revenue bonds due March 2013	Dec. 29, 2011 Industrial revenue bonds due March 2013 Maximum	Dec. 29, 2011 Industrial revenue bonds due March 2013 Minimum	Dec. 29, 2011 Industrial revenue bonds due April 2019	May 31, 2012 Industrial revenue bonds due April 2019	Dec. 29, 2011 Industrial revenue bonds due April 2019 Maximum	Dec. 29, 2011 Industrial revenue bonds due April 2019 Minimum	May 31, 2012 Unsecured Revolving Credit Facility	May 31, 2012 Credit Facility Expiring In May Twenty Thirteen	May 31, 2012 Line of Credit	May 31, 2012 Line of Credit Maximum	May 31, 2012 Worthington Nitin Cylinders Limited	May 31, 2012 Financial Stand-By Letters Of Credit	May 31, 2012 Accounts Receivable Facilities	May 31, 2011 Accounts Receivable Facilities	May 31, 2010 Accounts Receivable Facilities	Feb. 29, 2012 Accounts Receivable Facilities Day	Nov. 30, 2011 Accounts Receivable Facilities
Debt And Receivables Securitization [Line Items]
Maturity date																2017-05	2013-05			2012-11					2013-01
Maximum borrowing capacity																$ 425,000,000				$ 9,500,000		$ 150,000,000			$ 150,000,000	$ 100,000,000
Number of days past due trade accounts receivables are ineligible for securitization																									90
Borrowings outstanding																	400,000,000			4,313,000		135,000,000
Short term borrowings	274,923,000	132,956,000														135,610,000						135,000,000	90,000,000
Facility fee																						1,232,000	1,148,000	1,172,000
Debt maturity period							7 years												1 year
Average variable rate																		1.29%
Outstanding stand-by letters of credit amount for third-party beneficiaries																					10,982,000
Remaining borrowing capacity																		278,408,000
Applicable variable rate																				2.50%
Debt borrowings outstanding	258,791,000	250,254,000			100,000,000			620,000				2,490,000
Debt maturity date					Dec. 17, 2014	Apr. 15, 2020	May 01, 2019
Basis spread on variable rate					0.80%
Notional amount			100,000,000	100,000,000
Interest rate swap interest rate				4.46%
Debt instrument effective interest rate percentage after interest rate swap					5.26%
Principal amount						150,000,000	5,880,000
Debt interest rate						6.50%	2.49%			5.25%	3.75%			5.00%	2.75%
Percentage of principal amount debt instrument was sold to the public						99.89%
Yield to maturity						6.515%
Debt discount						165,000
Debt issuance cost						1,535,000
Settlement of hedge interest						1,358,000
Debt instrument maturity month and year								2013-03	2013-03			2019-04	2019-04
Debt instrument required monthly payments							$ 76,350	$ 28,000				$ 31,000