Goodwill and Other Long-Lived Assets - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended			3 Months Ended												3 Months Ended		12 Months Ended		1 Months Ended	3 Months Ended		12 Months Ended		3 Months Ended	12 Months Ended
	Nov. 30, 2013	May 31, 2014	May 31, 2013	May 31, 2012	May 31, 2013 Worthington Nitin Cylinders Limited	May 31, 2014 Worthington Nitin Cylinders Limited Noncontrolling Interest	May 31, 2013 Worthington Nitin Cylinders Limited Noncontrolling Interest	May 31, 2014 Zhejiang Nisshin Worthington Precision Specialty Steel Co	May 31, 2014 Aluminium High Pressure Cylinder Business	May 31, 2014 Long-lived assets held and used		May 31, 2013 Long-lived assets held and used		May 31, 2013 Long-lived assets held and used Worthington Nitin Cylinders Limited	May 31, 2014 Long-lived assets held and used Zhejiang Nisshin Worthington Precision Specialty Steel Co	May 31, 2014 Long-lived assets held and used Aluminium High Pressure Cylinder Business	May 31, 2014 Joint Venture Transactions Worthington Nitin Cylinders Limited	May 31, 2014 Joint Venture Transactions Long-lived assets held and used Worthington Nitin Cylinders Limited	May 31, 2014 Minimum	May 31, 2014 Maximum	Oct. 31, 2012 Pressure Cylinders	Nov. 30, 2013 Pressure Cylinders	Aug. 31, 2013 Pressure Cylinders	May 31, 2014 Pressure Cylinders	May 31, 2013 Pressure Cylinders	Nov. 30, 2013 Engineered Cabs	May 31, 2014 Engineered Cabs
Goodwill And Other Intangible Assets [Line Items]
Definite-lived intangible assets, estimated useful lives																			1 year	20 years
Impairment of long-lived assets	$ 30,734,000	$ 58,246,000	$ 6,488,000	$ 355,000				$ 7,141,000	$ 1,412,000												$ 1,520,000	$ 11,634,000	$ 1,570,000			$ 19,100,000
Amortization expense		17,386,000	10,467,000	5,229,000
Percent of controlling interest by the company																	60.00%
Asset measured at fair value on nonrecurring basis		32,074,000	6,856,000							7,034,000	[1]	6,856,000	[2]	6,856,000	19,115,000	7,034,000		5,925,000
Impairment of long-lived assets		58,246,000	6,488,000	355,000	4,968,000	7,583,000	1,987,000										18,959,000							32,005,000	6,488,000		19,100,000
Gain/loss on sale of assets		$ (10,589,000)	$ (1,886,000)																		$ 50,000

[1] During the fourth quarter of fiscal 2014, we determined that indicators of impairment were present at the Company's aluminum high-pressure cylinder business in New Albany, Mississippi, due to current and projected operating losses. Recoverability of the identified asset group was tested using future cash flow projections based on management's long-range estimates of market conditions. The sum of these undiscounted future cash flows was less than the net book value of the asset group. In accordance with the applicable accounting guidance, the net assets were written down to their fair value of $7,034,000, resulting in an impairment charge of $1,412,000 within impairment of long-lived assets in our fiscal 2014 consolidated statement of earnings.

[2] During the fourth quarter of fiscal 2013, the long-lived assets of our 60%-owned consolidated joint venture in India, Worthington Nitin Cylinders, were written down to their estimated fair value of $6,856,000, resulting in an impairment charge of $4,968,000 within impairment of long-lived assets in our consolidated statement of earnings. The portion of this impairment loss attributable to the noncontrolling interest, or $1,987,000, was recorded within net earnings attributable to noncontrolling interest in our consolidated statement of earnings. Fair value was determined based on market prices for similar assets.