Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended							1 Months Ended	3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended					12 Months Ended						1 Months Ended				1 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended
	May 31, 2012 Facility Country State	May 31, 2012 Facility Country State	May 31, 2011	May 31, 2010	May 31, 2012 Building and Improvements Maximum	May 31, 2012 Building and Improvements Minimum	May 31, 2012 Machinery and Equipment Maximum	May 31, 2012 Machinery and Equipment Minimum	Mar. 02, 2011 Metal Framing Facility	May 31, 2011 Metal Framing	May 31, 2011 Metal Framing	May 31, 2010 Metal Framing	May 31, 2012 Metal Framing	May 31, 2012 Global Group	May 31, 2012 Global Group Maximum	May 31, 2011 Global Group Maximum	May 31, 2010 Global Group Maximum	May 31, 2012 Automotive Market Net Sales	May 31, 2012 Foreign Operations	May 31, 2012 Foreign Operations Net Sales	May 31, 2012 Foreign Operations Pre-tax earnings	May 31, 2012 Collective Bargaining Agreements	May 31, 2012 Largest Customer Customer	May 31, 2012 Largest Customer Net Sales	May 31, 2012 Ten Largest Customers Net Sales	Mar. 02, 2011 ClarkDietrich Metal Framing Facility	May 31, 2012 Joint Venture Transactions Spartan Steel Coating, LLC	May 31, 2012 Joint Venture Transactions Worthington Nitin Cylinders Limited	May 31, 2012 Joint Venture Transactions PSI Energy Solutions, LLC	May 09, 2011 Joint Venture Transactions ArtiFlex	May 31, 2011 Joint Venture Transactions ArtiFlex	Mar. 02, 2011 Joint Venture Transactions ClarkDietrich	May 31, 2011 Joint Venture Transactions ClarkDietrich
Significant Accounting Policies [Line Items]
Percent of controlling interest by the Company																											52.00%	60.00%	75.00%
Impairment of long-lived assets		$ 355,000	$ 4,386,000	$ 35,409,000						$ 18,293,000				$ 355,000																$ 6,414,000	$ 6,414,000	$ 18,293,000	$ 18,293,000
Percent of interest by unconsolidated affiliates																														50.00%		25.00%
Gain on Deconsolidation																														15,040,000		31,319,000
Number of facilities									13																	6
Carrying value of asset group													7,202,000
Restructuring charges		5,984,000	2,653,000	4,243,000							1,387,000	3,892,000																				11,216,000	11,216,000
Employee severance cost	1,143,000																																7,183,000
Facility exit and other costs incurred		9,116,000																															4,033,000
Number of production facilities operated	79	79
Number of States operated	19	19
Number of Countries operated	12	12
Concentration risk percentage																		34.00%		8.00%	4.00%			5.00%	24.00%
Percentage of consolidated net assets																			30.00%
Percentage of labor force																						6.00%
Number of customers																							10
Allowance for doubtful accounts decreased		(821,000)
Receivables, allowances	3,329,000	3,329,000	4,150,000
Property, plant and equipment, estimated useful life					40 years	10 years	20 years	3 years
Depreciation Expenses		50,644,000	57,765,000	60,529,000
Percentage of consolidated net sales contributed															5.00%	5.00%	5.00%
Advertising Expenses		$ 4,788,000	$ 3,817,000	$ 3,838,000