Acquisitions - Allocations of Intevras and Bencor Purchase Price (Detail) (USD $)	Jul. 27, 2010 Intevras Technologies [Member]	Oct. 22, 2010 Bencor [Member]	Jan. 31, 2011 Intevras and Bencor [Member]
Business Acquisition [Line Items]
Working capital	$ 113,000	$ 8,683,000	$ 8,796,000
Property and equipment	556,000	18,451,000	19,007,000
Goodwill	1,891,000	8,529,000	10,420,000
Other intangible assets	4,040,000	5,040,000	9,080,000
Other assets		39,000	39,000
Deferred taxes		(7,023,000)	(7,023,000)
Other noncurrent liabilities		(795,000)	(795,000)
Noncontrolling interest in subsidiary of Bencor		(851,000)	(851,000)
Total purchase price	$ 6,600,000	$ 32,073,000	$ 38,673,000