Impairment of Long-Lived Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended
	Nov. 30, 2013	Aug. 31, 2013	Feb. 28, 2014	Feb. 28, 2013	Oct. 31, 2012 Pressure Cylinders	Aug. 31, 2013 Pressure Cylinders	Feb. 28, 2014 Pressure Cylinders	Feb. 28, 2013 Pressure Cylinders	Aug. 31, 2013 Long-lived assets held and used
Goodwill And Other Intangible Assets [Line Items]
Impairment of long-lived assets	$ 30,734,000	$ 4,641,000	$ 35,375,000	$ 1,520,000	$ 1,520,000	$ 1,570,000	$ 11,634,000	$ 1,520,000
Asset measured at fair value on nonrecurring basis						6,934,000			11,827,000
Gain/loss on sale of assets			$ 10,587,000		$ 50,000