Investments in Unconsolidated Affiliates - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Aug. 31, 2012	May 31, 2012
Investments in and Advances to Affiliates [Line Items]
Distributions from unconsolidated affiliates	$ 15,286,000
WAVE
Investments in and Advances to Affiliates [Line Items]
Cumulative distributions in excess of investment	$ 64,801,000	$ 69,165,000
Joint Venture Transactions | ArtiFlex
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	50.00%
Joint Venture Transactions | ClarkDietrich
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	25.00%
Joint Venture Transactions | Gestamp Worthington Wind Steel, LLC
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	50.00%
Joint Venture Transactions | Samuel Steel Pickling Company
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	31.00%
Joint Venture Transactions | Seviacero
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	50.00%
Joint Venture Transactions | TWB
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	45.00%
Joint Venture Transactions | WAVE
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	50.00%
Joint Venture Transactions | Worthington Modern Steel Framing Manufacturing Co., Ltd.
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	40.00%
Joint Venture Transactions | Worthington Specialty Processing
Investments in and Advances to Affiliates [Line Items]
Percent of interest by unconsolidated affiliates	51.00%