Acquisitions and Divestitures - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jul. 31, 2013
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Business Combination, Acquisition Related Costs		$ 3,600		$ 3,600
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory				1,530
Proceeds from sale of operations			0	10,178
Loss (gain) on sales of businesses			0	(3,138)
Net sales	291,194	272,702	598,724	544,717
Net earnings (loss), as reported	16,424	(8,684)	40,353	18,504
Proceeds from borrowing on notes payable		220,000	(3,187)	0
Repayment of borrowing on notes payable			30,000	112,472	(211,000)
Customer relationships	102,500		102,500		102,500
Goodwill, Fair Value Disclosure	168,150		168,150		168,150
Finite-Lived Trade Names, Gross	6,800		6,800		6,800
Interest expense	(3,676)	(4,406)	(7,397)	(8,569)
Income tax expense (benefit)	4,408	28,960	13,002	42,138
Amortization of Intangible Assets			5,047	5,015
Business Acquisition, Goodwill, Expected Tax Deductible Amount	57,374		57,374		57,374
Business Acquistition Purchase Price Allocation Intangibles Exepcted Tax Deductible	51,672		51,672		51,672
Depreciation and amortization			22,342	22,046
Notes payable	23,946		23,946		23,946	50,613
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	109,300		109,300		109,300
Finite-lived customer relationships [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Finite-Lived Intangible Asset, Useful Life			10 years
Trademarks [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Finite-Lived Intangible Asset, Useful Life			3 years
Precision Dynamics Corporation [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Interest expense		320		529
Income tax expense (benefit)		564		(135)
Depreciation and amortization		3,104		6,208
USD-Denominated Borrowing Credit Revolver [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Notes Payable	39,000		39,000		39,000
Notes Payable	9,000		9,000		9,000
Revolving Credit Facility [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Notes payable	9,000		9,000		9,000	39,000
USD-denominated credit facility China [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Notes payable	$ 14,946		$ 14,946		$ 14,946