Product Warranties (Schedule Of Changes In Product Warranty Reserves) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2012	Jan. 31, 2011
Product Warranties [Abstract]
Beginning balance	$ 66,322	$ 62,474	$ 66,054	$ 51,467
Provision	12,461	13,757	29,533	28,123
Payments	(16,763)	(14,651)	(33,567)	(28,189)
Heartland acquisition				10,179
Ending balance	$ 62,020	$ 61,580	$ 62,020	$ 61,580
Warranty period for retail customers, years			1 year
Period of longer warranty for structural components			5 years