Guarantees, Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended						1 Months Ended	6 Months Ended		1 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014 Minimum	Jan. 31, 2014 Maximum	Jan. 31, 2014 Product Extended Warranty Contracts	Jul. 31, 2013 Product Extended Warranty Contracts	Oct. 11, 2011 Credit Agreement	Jan. 31, 2014 Credit Agreement	Jan. 31, 2014 Credit Agreement Other Revolving Credit Facilities	Oct. 11, 2011 Credit Agreement Minimum	Jan. 31, 2014 Credit Agreement Minimum	Oct. 11, 2011 Credit Agreement Maximum	Jan. 31, 2014 Credit Agreement Maximum	Oct. 11, 2011 Credit Agreement Libor Rate Minimum	Oct. 11, 2011 Credit Agreement Libor Rate Maximum	Oct. 11, 2011 Credit Agreement Defined Base Rate Minimum	Oct. 11, 2011 Credit Agreement Defined Base Rate Maximum
Commitments and Contingencies Disclosure [Line Items]
Liabilities related to agreements	$ 0		$ 0
Standard product warranty term					12 months	36 months
Deferred revenue for product extended warranty contracts							10.3	8.0
Revolving credit agreement period									5 years
Credit facility maximum borrow capacity									100.0
Credit facility, expiry date									Oct. 10, 2016
Aggregate available credit amount under specified circumstances														150.0
Percentage of capital stock pledge as collateral									65.00%
Variable interest rate																1.25%	2.00%	0.00%	1.00%
Credit facility commitment fee percentage												0.20%		0.35%
Leverage ratio of total debt to earnings before interest tax depreciation amortization															275.00%
Interest coverage ratio													300.00%
Leverage ratio										0.006%
Credit facility transaction costs incurred										0.5
Credit facility, maturity period										5 years
Credit facility available borrowing capacity											4.3
Borrowing outstanding under credit facilities		0		0
Business exit cost	$ 0.6	$ 0.3	$ 0.9	$ 0.4