Warranty (Reconciliation Of Warranty Reserves) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jan. 31, 2012	Jan. 31, 2011
Warranty [Abstract]
Balance at beginning of year	$ 19,720	$ 15,707
Accruals for warranties issued during the reporting period	1,826	3,436
Adjustments related to pre - existing warranties (including changes in estimates)	(1,294)	2,367
Less settlements made during the period	(5,638)	(4,342)
Balance at end of period	$ 14,614	$ 17,168