Goodwill and Intangible Assets - Other Intangibles Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015	Jul. 31, 2015
Other Intangible Assets [Line Items]
Gross Carrying Amount	$ 193,836		$ 193,836		$ 195,569
Accumulated Amortization	(130,206)		(130,206)		(126,681)
Net Book Value	63,630		63,630		$ 68,888
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Intangible Assets	2,595	$ 2,982	5,228	$ 6,351
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	8,794		8,794
Finite-Lived Intangible Assets, Amortization Expense, Year Two	7,117		7,117
Finite-Lived Intangible Assets, Amortization Expense, Year Three	6,442		6,442
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6,166		6,166
Finite-Lived Intangible Assets, Amortization Expense, Year Five	5,640		$ 5,640
Patents [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			5 years		5 years
Gross Carrying Amount	12,147		$ 12,147		$ 12,073
Accumulated Amortization	(10,851)		(10,851)		(10,641)
Net Book Value	1,296		$ 1,296		$ 1,432
Trademarks And Other [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			5 years		5 years
Gross Carrying Amount	14,270		$ 14,270		$ 14,375
Accumulated Amortization	(13,668)		(13,668)		(12,471)
Net Book Value	602		$ 602		$ 1,904
Customer relationships [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			7 years		7 years
Gross Carrying Amount	135,283		$ 135,283		$ 136,693
Accumulated Amortization	(96,784)		(96,784)		(94,537)
Net Book Value	38,499		$ 38,499		$ 42,156
Non-compete agreements and other [Member]
Other Intangible Assets [Line Items]
Weighted Average Amortization Period			4 years		4 years
Gross Carrying Amount	8,922		$ 8,922		$ 9,076
Accumulated Amortization	(8,903)		(8,903)		(9,032)
Net Book Value	19		19		44
Trademarks [Member]
Other Intangible Assets [Line Items]
Gross Carrying Amount	23,214		23,214		23,352
Accumulated Amortization	0		0		0
Net Book Value	$ 23,214		$ 23,214		$ 23,352