Stock-Based Compensation Plans (Schedule Of Fair Value Assumptions Of Options) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Stock-Based Compensation Plans [Abstract]
Expected life (years)	10 years	10 years	10 years	10 years
Risk-free interest rate	1.70%	2.00%	1.70%	2.10%
Expected volatility	130.60%	125.50%	130.50%	123.90%
Expected forfeiture rate	11.70%	24.80%	13.50%	21.20%
Expected dividend yield
Weighted-average estimated fair value of options granted during the year	$ 1.29	$ 1.04	$ 1.25	$ 0.96