Impairment of Long-Lived Assets - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Aug. 31, 2012	Feb. 28, 2013	Oct. 31, 2012
Impaired Long Lived Assets Held For Disposed Off By Type [Line Items]
Impairment of long-lived assets		$ 1,520,000
Gain on sale of long lived assets		1,886,000
Pressure Cylinders
Impaired Long Lived Assets Held For Disposed Off By Type [Line Items]
Assets held for sale, long lived assets	6,934,000
Impairment of long-lived assets	1,570,000	1,520,000
Gain on sale of long lived assets			50,000
Joint Venture Transactions
Impaired Long Lived Assets Held For Disposed Off By Type [Line Items]
Carrying value of the asset group tested for recoverability		$ 7,488,000