Components of Amortizable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Apr. 30, 2013	Jul. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Cost	$ 131,535	$ 136,626
Accumulated Amortization	27,359	22,399
Dealer Networks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	10 years
Cost	68,310	72,230
Accumulated Amortization	17,530	13,343
Non-Compete Agreements
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	3 years
Cost	4,130	6,321
Accumulated Amortization	2,168	3,678
Trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	22 years
Cost	37,775	36,775
Accumulated Amortization	3,646	2,522
Design Technology And Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	12 years
Cost	21,320	21,300
Accumulated Amortization	$ 4,015	$ 2,856