Debt and Receivables Securitization - Additional Information (Detail) - USD ($)								1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 23, 2015	Oct. 15, 2014	Sep. 26, 2014	Apr. 15, 2014	Aug. 10, 2012	Apr. 27, 2012	Apr. 13, 2010	May. 31, 2015	Feb. 28, 2015	May. 31, 2015	May. 31, 2014	May. 31, 2013
Debt And Receivables Securitization [Line Items]
Borrowings outstanding								$ 24,915,000		$ 24,915,000
Short-term borrowings								$ 90,550,000		$ 90,550,000	$ 10,362,000
Unsecured Senior Notes, Four Point Five Five Percent, Due April Fifteen Twenty Twenty Six
Debt And Receivables Securitization [Line Items]
Principal amount				$ 250,000,000
Debt, maturity date				Apr. 15, 2026						Apr. 15, 2026	Apr. 15, 2026
Debt, interest rate				4.55%				4.55%		4.55%	4.55%
Percentage of principal amount debt instrument was sold to the public				99.789%
Yield to maturity				4.573%
Debt discount				$ 528,000				$ 476,000		$ 476,000
Debt issuance cost				2,256,000
Settlement of hedge interest				$ 3,081,000
Unamortized portion of debt issuance costs								$ 1,881,000		$ 1,881,000
4.60% senior notes due August 10, 2024
Debt And Receivables Securitization [Line Items]
Principal amount					$ 150,000,000
Debt, maturity date					Aug. 10, 2024					Aug. 10, 2024	Aug. 10, 2024
Debt, interest rate					4.60%			4.60%		4.60%	4.60%
6.50% Unsecured Senior Notes due April 15, 2020
Debt And Receivables Securitization [Line Items]
Principal amount							$ 150,000,000
Debt, maturity date							Apr. 15, 2020
Debt, interest rate							6.50%
Yield to maturity							6.515%
Debt discount							$ 165,000	$ 80,000		$ 80,000
Debt issuance cost							1,535,000
Settlement of hedge interest							$ 1,358,000
Unamortized portion of debt issuance costs								582,000		582,000
Percentage of principal amount debt instrument was sold to the public							99.89%
Term Loan maturing May 1, 2019
Debt And Receivables Securitization [Line Items]
Maximum borrowing capacity						$ 5,880,000
Borrowings outstanding								3,416,000		$ 3,416,000
Debt, maturity date										May 01, 2019
Debt, interest rate						2.49%
Term loan credit facility, term						7 years
Debt instrument required monthly payments						$ 76,350
Securities Sold under Agreements to Repurchase
Debt And Receivables Securitization [Line Items]
Maturity date									2018-01
Maximum borrowing capacity								100,000,000		$ 100,000,000
Number of days past due trade accounts receivables are ineligible for securitization										90 days
Borrowings outstanding								$ 60,000,000		$ 60,000,000
Facility fee										$ 723,000	$ 652,000	$ 983,000
Interest Rate Swap
Debt And Receivables Securitization [Line Items]
Borrowings outstanding		$ 16,809,000
Interest rate swap, interest rate		2.015%
Interest rate swap, start date		Dec. 26, 2014
Interest rate swap, maturity date		Sep. 26, 2019
Unsecured Revolving Credit Facility
Debt And Receivables Securitization [Line Items]
Line of credit, variable rate								1.39%		1.39%
Unsecured Revolving Credit Facility | Amended Credit Facility
Debt And Receivables Securitization [Line Items]
Maturity date										2020-04
Maximum borrowing capacity	$ 500,000,000
Credit facility, increased capacity under the credit agreement	$ 75,000,000
Credit facility, extension in maturity period	3 years
Unsecured Revolving Credit Facility | Maximum
Debt And Receivables Securitization [Line Items]
Debt maturity period	1 year
Worthington Aritas
Debt And Receivables Securitization [Line Items]
Maximum borrowing capacity			$ 28,028,000
Borrowings outstanding								$ 27,013,000		$ 27,013,000
Line of credit, variable rate								1.519%		1.519%
Term loan credit facility, term			5 years
Worthington Nitin Cylinders
Debt And Receivables Securitization [Line Items]
Maturity date								2014-11
Maximum borrowing capacity								$ 9,500,000		$ 9,500,000
Line of credit, variable rate								15.25%		15.25%
Short-term borrowings								$ 5,635,000		$ 5,635,000