Goodwill and Intangible Assets - Other Intangible Asset (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jan. 31, 2013	Jul. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 355,541	$ 244,493
Accumulated Amortization	(170,046)	(160,374)
Net Book Value	185,495	84,119
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	5 years	5 years
Gross Carrying Amount	10,679	10,418
Accumulated Amortization	(9,352)	(9,058)
Net Book Value	1,327	1,360
Trademarks and other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	5 years	7 years
Gross Carrying Amount	15,815	8,945
Accumulated Amortization	(7,196)	(7,094)
Net Book Value	8,619	1,851
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	8 years	7 years
Gross Carrying Amount	267,905	164,392
Accumulated Amortization	(138,227)	(128,805)
Net Book Value	129,678	35,587
Non-compete agreements and other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	4 years	4 years
Gross Carrying Amount	15,714	15,988
Accumulated Amortization	(15,271)	(15,417)
Net Book Value	443	571
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	45,428	44,750
Accumulated Amortization	0	0
Net Book Value	$ 45,428	$ 44,750