Guarantees, Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 11, 2011	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013	Jul. 31, 2013
Commitments and Contingencies Disclosure [Line Items]
Liabilities related to agreements		$ 0		$ 0
Revolving credit agreement period	5 years
Borrowing outstanding under credit facilities		0		0		0
Business exit cost		0.4	0.3	1.3	0.7
Minimum
Commitments and Contingencies Disclosure [Line Items]
Standard product warranty term				12 months
Maximum
Commitments and Contingencies Disclosure [Line Items]
Standard product warranty term				36 months
Product Extended Warranty Contracts
Commitments and Contingencies Disclosure [Line Items]
Deferred revenue for product extended warranty contracts		9.2		9.2		8.0
Credit Agreement
Commitments and Contingencies Disclosure [Line Items]
Credit facility maximum borrow capacity	100.0
Credit facility, expiry date	Oct. 10, 2016
Percentage of capital stock pledge as collateral	65.00%
Leverage ratio		0.006%		0.006%
Credit facility transaction costs incurred		0.5		0.5
Credit facility, maturity period				5 years
Credit Agreement | Other Revolving Credit Facilities
Commitments and Contingencies Disclosure [Line Items]
Credit facility available borrowing capacity		4.2		4.2
Credit Agreement | Minimum
Commitments and Contingencies Disclosure [Line Items]
Credit facility commitment fee percentage	0.20%
Interest coverage ratio		300.00%		300.00%
Credit Agreement | Maximum
Commitments and Contingencies Disclosure [Line Items]
Aggregate available credit amount under specified circumstances	$ 150.0
Credit facility commitment fee percentage	0.35%
Leverage ratio of total debt to earnings before interest, taxes, depreciation, and amortization or EBITDA				275.00%
Credit Agreement | Libor Rate | Minimum
Commitments and Contingencies Disclosure [Line Items]
Variable interest rate	1.25%
Credit Agreement | Libor Rate | Maximum
Commitments and Contingencies Disclosure [Line Items]
Variable interest rate	2.00%
Credit Agreement | Defined Base Rate | Minimum
Commitments and Contingencies Disclosure [Line Items]
Variable interest rate	0.00%
Credit Agreement | Defined Base Rate | Maximum
Commitments and Contingencies Disclosure [Line Items]
Variable interest rate	1.00%