Goodwill and Intangible Assets - Other Intangibles Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014	Jul. 31, 2014
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Amortization of Intangible Assets	$ 2,982	$ 5,047	$ 6,351	$ 10,124
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	11,747		11,747
Finite-Lived Intangible Assets, Amortization Expense, Year Two	9,660		9,660
Finite-Lived Intangible Assets, Amortization Expense, Year Three	7,391		7,391
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6,640		6,640
Finite-Lived Intangible Assets, Amortization Expense, Year Five	6,355		6,355
Other Intangible Assets [Line Items]
Gross Carrying Amount	202,688		202,688		235,865
Accumulated Amortization	(121,162)		(121,162)		(144,851)
Net Book Value	81,526		81,526		91,014
Patents [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			5 years		5 years
Gross Carrying Amount	11,769		11,769		11,656
Accumulated Amortization	(10,353)		(10,353)		(10,160)
Net Book Value	1,416		1,416		1,496
Trademarks And Other [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			5 years		5 years
Gross Carrying Amount	14,562		14,562		15,366
Accumulated Amortization	(11,364)		(11,364)		(10,706)
Net Book Value	3,198		3,198		4,660
Customer relationships [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			7 years		7 years
Gross Carrying Amount	138,218		138,218		168,525
Accumulated Amortization	(90,205)		(90,205)		(114,363)
Net Book Value	48,013		48,013		54,162
Non-compete agreements and other [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			4 years		4 years
Gross Carrying Amount	9,338		9,338		10,089
Accumulated Amortization	(9,240)		(9,240)		(9,622)
Net Book Value	98		98		467
Trademarks [Member]
Other Intangible Assets [Line Items]
Gross Carrying Amount	28,801		28,801		30,229
Accumulated Amortization	0		0		0
Net Book Value	$ 28,801		$ 28,801		$ 30,229