Components of Amortizable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2012	Jul. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Cost	$ 136,454	$ 136,626
Accumulated Amortization	23,094	22,399
Dealer Networks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	10 years
Cost	73,130	72,230
Accumulated Amortization	15,132	13,343
Non-Compete Agreements
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	3 years
Cost	4,250	6,321
Accumulated Amortization	1,819	3,678
Trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	22 years
Cost	37,774	36,775
Accumulated Amortization	2,906	2,522
Design Technology And Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	12 years
Cost	21,300	21,300
Accumulated Amortization	$ 3,237	$ 2,856