Fair Values (Narrative) (Details) (USD $)
3 Months Ended 6 Months Ended
Jan. 31, 2015
Jan. 31, 2014
Jan. 31, 2015
Jan. 31, 2014
Jul. 31, 2014
Debt Instrument [Line Items]          
Aggregate carrying amount of equity method investments $ 20,100,000   $ 20,100,000   $ 21,400,000
Impairment charges 0 0 0 0  
Long-Term Debt [Member]          
Debt Instrument [Line Items]          
Fair value of debt 245,200,000   245,200,000    
Debt carrying amount $ 225,000,000   $ 225,000,000