Acquisitions and Divestitures - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended			1 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended
	Jan. 31, 2013	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012	Dec. 28, 2012	Aug. 31, 2012 Brady Medical [Member]	Oct. 31, 2012 Brady Medical [Member]	Oct. 31, 2012 Varitronics [Member]	Oct. 31, 2012 Varitronics [Member]	Apr. 30, 2013 Precision Dynamics Corporation [Member]	Apr. 30, 2013 Precision Dynamics Corporation [Member]	Apr. 30, 2013 Precision Dynamics Corporation [Member]	Apr. 30, 2012 Precision Dynamics Corporation [Member]	Apr. 30, 2013 Finite-lived customer relationships [Member]	Apr. 30, 2013 Trademarks [Member]	Apr. 30, 2013
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Notes Payable																	$ 11,658
Proceeds from sale of operations				10,178	0		3,378		8,410
Cash							3,018
Non-cash consideration							360
Loss (gain) on sales of businesses				(3,138)	0			(3,675)		237
Proceeds from cash distribution									7,160
Proceeds in the form of a promissory note									1,250
Net sales		305,737	275,388	856,408	813,573						40,682	56,750
Net (loss) income, as reported		4,233	27,652	22,736	(29,570)						1,865	626
Assets, fair value adjustment		16,788		16,788							1,530	1,530	1,530	1,530
Proceeds from borrowing on notes payable		220,000		220,000	0
Repayment of borrowing on notes payable				173,000	0
Expected completion of valuation	12
Customer relationships						102,500
Finite-Lived Intangible Asset, Useful Life															10 years	3 years
Finite-Lived Trade Names, Gross						6,800
Goodwill		189,187	1,227	189,187	1,227
Business Combination, Acquisition Related Costs													3,600	3,600
Interest Expense		4,185	4,735	12,755	14,715								529	720
Income tax expense (benefit)													(135)	(827)
Amortization of Intangible Assets		$ 6,597	$ 3,944	$ 15,759	$ 12,102								$ 9,313