Financial Instruments (Narrative) (Details) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Amount of losses recorded due to exclusion of forward points assessment of hedge effectiveness	$ 1,100,000	$ 200,000	$ 400,000
Expected net deferred gains from forward exchange contracts	200,000
Estimated fair value of long-term debt with fixed interest rates	268,300,000
Carrying value of long-term debt fixed interest rate	253,619,000	261,728,000
Interest rate swaps outstanding	0	1
Fixed Interest Rate [Member]
Estimated fair value of long-term debt with fixed interest rates	268,300,000
Carrying value of long-term debt fixed interest rate	$ 247,000,000