Guarantees, Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended						1 Months Ended	3 Months Ended		1 Months Ended		1 Months Ended	3 Months Ended	1 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013 Minimum	Oct. 31, 2013 Maximum	Oct. 31, 2013 Product Extended Warranty Contracts	Jul. 31, 2013 Product Extended Warranty Contracts	Oct. 11, 2011 Credit Agreement	Oct. 31, 2013 Credit Agreement	Oct. 31, 2013 Credit Agreement Other Revolving Credit Facilities	Oct. 11, 2011 Credit Agreement Minimum	Oct. 31, 2013 Credit Agreement Minimum	Oct. 11, 2011 Credit Agreement Maximum	Oct. 31, 2013 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]
Standard product warranty term			12 months	36 months
Deferred revenue for product extended warranty contracts					$ 9.0	$ 8.0
Revolving credit agreement period							5 years
Credit facility maximum borrow capacity							100
Credit facility, expiry date							Oct. 10, 2016
Aggregate available credit amount under specified circumstances												150
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								0.60%
Credit facility transaction costs incurred								0.5
Credit facility, maturity period								5 years
Credit facility available borrowing capacity									4.2
Business exit cost	$ 0.3	$ 0.1