Basis of Presentation - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Nov. 30, 2015 USD ($)	Nov. 30, 2016 USD ($) Entity	Nov. 30, 2015 USD ($)	May 31, 2016 USD ($)
Accounting Standards Update 2015-03
Significant Accounting Policies [Line Items]
Debt issuance cost		$ 2,319,000		$ 2,491,000
Accounting Standards Update 2016-09
Significant Accounting Policies [Line Items]
Excess tax benefits associated with share-based payments	$ 136,000		$ 694,000
Amended accounting guidance, description		In March 2016, amended accounting guidance was issued that simplifies the accounting for share-based payments. The amended guidance impacts several aspects of the accounting for share-based payment transactions, including the income tax consequences, forfeitures, statutory withholding requirements, and classification in the statement of cash flows. The Company early adopted this guidance during the fourth quarter of fiscal 2016. As required for early adoption in an interim period, all adjustments have been reflected as of the beginning of fiscal 2016. Accordingly, income tax expense for the three and six months ended November 30, 2015 has been restated to reflect excess tax benefits associated with share-based payments totaling $136,000 and $694,000, respectively, in current income tax expense, rather than in paid-in capital.
Joint Venture Transactions
Significant Accounting Policies [Line Items]
Number of joint ventures | Entity		6
DHybrid Systems LLC | Joint Venture Transactions
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company		79.59%
Spartan | Joint Venture Transactions
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company		52.00%
TWB | Joint Venture Transactions
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company		55.00%
Worthington Aritas | Joint Venture Transactions
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company		75.00%
WEI | Joint Venture Transactions
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company		75.00%
Worthington Specialty Processing | Joint Venture Transactions
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company		51.00%