Intangibles (detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013	Jul. 31, 2013	Apr. 30, 2014 Patents [Member]	Jul. 31, 2013 Patents [Member]	Apr. 30, 2014 Trademarks and other [Member]	Jul. 31, 2013 Trademarks and other [Member]	Apr. 30, 2014 Customer relationships [Member]	Jul. 31, 2013 Customer relationships [Member]	Apr. 30, 2014 Non-compete agreements and other [Member]	Jul. 31, 2013 Non-compete agreements and other [Member]	Apr. 30, 2014 Trademarks [Member]	Jul. 31, 2013 Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period						5 years	5 years	5 years	5 years	8 years	8 years	4 years	4 years
Gross Carrying Amount	$ 331,316		$ 331,316		$ 333,681	$ 11,428	$ 11,053	$ 15,833	$ 15,289	$ 259,383	$ 261,076	$ 13,490	$ 14,942	$ 31,182	$ 31,321
Accumulated Amortization	(188,470)		(188,470)		(176,830)	(10,025)	(9,597)	(10,489)	(8,398)	(155,093)	(144,620)	(12,863)	(14,215)	0	0
Net Book Value	142,846		142,846		156,851	1,403	1,456	5,344	6,891	104,290	116,456	627	727	31,182	31,321
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Amortization of Intangible Assets	4,713	5,007	14,837	11,020
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	19,579		19,579
Finite-Lived Intangible Assets, Amortization Expense, Year Two	18,746		18,746
Finite-Lived Intangible Assets, Amortization Expense, Year Three	16,531		16,531
Finite-Lived Intangible Assets, Amortization Expense, Year Four	13,318		13,318
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 11,981		$ 11,981