Fair Values (Narrative) (Details) (USD $)	Jul. 31, 2012	Jul. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of long-term debt fixed interest rate	$ 205,829,000	$ 253,619,000
Aggregate carrying amoung	20,100,000	19,200,000
Fixed Interest Rate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair value of long-term debt with fixed interest rates	223,500,000
Carrying value of long-term debt fixed interest rate	$ 201,100,000