Annual report pursuant to Section 13 and 15(d)

Income taxes (Details) - Benefit (provision) for income taxes were at rates different from U.S. federal statutory rates

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Income taxes (Details) - Benefit (provision) for income taxes were at rates different from U.S. federal statutory rates
12 Months Ended
Jul. 31, 2014
Jul. 31, 2013
Jul. 31, 2012
Benefit (provision) for income taxes were at rates different from U.S. federal statutory rates [Abstract]      
Federal statutory rate 34.00% 34.00% 34.00%
Penalties and other expenses not deductible for income tax return purposes (6.60%) (0.90%) (0.50%)
State income taxes, net of benefit of federal tax deduction 0.20% 2.50% 0.90%
Change in valuation allowance (16.50%) (32.70%) (23.20%)
Impairment of goodwill     (7.10%)
State tax law change (12.30%)    
Other 0.50% 0.90% (0.10%)
(0.70%) 3.80% 4.00%