Summary of Changes in Carrying Amount of Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended				12 Months Ended
May 31, 2012	May 31, 2011	May 31, 2012 Pressure Cylinders	May 31, 2011 Pressure Cylinders	May 31, 2012 Engineered Cabs	May 31, 2012 Metal Framing	May 31, 2011 Metal Framing	May 31, 2010 Metal Framing	May 31, 2012 Other	May 31, 2010 Other
Goodwill [Line Items]
Goodwill, beginning balance	$ 215,227	$ 201,137	$ 93,633	$ 79,543		$ 96,943	$ 96,943	$ 96,943	$ 24,651	$ 24,651
Accumulated impairment losses, beginning balance	(121,594)	(121,594)				(96,943)	(96,943)	(96,943)	(24,651)	(24,651)
Goodwill net, beginning balance	93,633	79,543	93,633	79,543
Acquisitions and purchase accounting adjustments	68,611	11,536	17,730	11,536	45,230				5,651
Translation adjustments	(5,563)	2,554	(5,563)	2,554
Goodwill, ending balance	278,275	215,227	105,800	93,633	45,230	96,943	96,943	96,943	30,302	24,651
Accumulated impairment losses, ending balance	(121,594)	(121,594)				(96,943)	(96,943)	(96,943)	(24,651)	(24,651)
Goodwill net, ending balance	$ 156,681	$ 93,633	$ 105,800	$ 93,633	$ 45,230				$ 5,651

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 34

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ References+ Details