Warranties (Details) (USD $)	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Summary of activity in warranty reserves
Beginning balance	$ 1,261,000	$ 1,667,000
Provisions	691,000	367,000
Settlements	(691,000)	(596,000)
Ending Balance	$ 1,261,000	$ 1,438,000