Annual report pursuant to Section 13 and 15(d)

Income taxes (Details) - Components of loss before income taxes

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Income taxes (Details) - Components of loss before income taxes (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Jul. 31, 2013
Apr. 30, 2013
Jan. 31, 2013
Oct. 31, 2012
Jul. 31, 2012
Apr. 30, 2012
Jan. 31, 2012
Oct. 31, 2011
Jul. 31, 2013
Jul. 31, 2012
Jul. 31, 2011
Income taxes (Details) - Components of loss before income taxes [Line Items]                      
Loss before taxes $ (3,532) $ (5,808) $ (5,854) $ (3,755) $ (29,074) $ (3,445) $ (4,076) $ (4,326) $ (18,949) $ (40,921) $ (12,823)
Domestic Tax Authority [Member]
                     
Income taxes (Details) - Components of loss before income taxes [Line Items]                      
Loss before taxes                 (15,419) (31,817) (12,284)
Foreign Tax Authority [Member]
                     
Income taxes (Details) - Components of loss before income taxes [Line Items]                      
Loss before taxes                 $ (3,530) $ (9,104) $ (539)