Components of Amortizable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jan. 31, 2013	Jul. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Cost	$ 137,555	$ 136,626
Accumulated Amortization	25,890	22,399
Dealer Networks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	10 years
Cost	73,540	72,230
Accumulated Amortization	16,930	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	2,032	3,678
Trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life in Years	22 years
Cost	38,445	36,775
Accumulated Amortization	3,306	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	$ 3,622	$ 2,856