Annual report pursuant to Section 13 and 15(d)

Stockholders' equity (Detail) - Stock option plans

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Stockholders' equity (Detail) - Stock option plans (USD $)
12 Months Ended
Jul. 31, 2012
Jul. 31, 2011
Jul. 31, 2010
Outstanding at beginning of year 785,124 1,132,450 1,191,519
Outstanding at beginning of year (in Dollars per share) $ 14.53 $ 14.30 $ 14.41
Cancelled (48,634) (347,326) (59,069)
Cancelled (in Dollars per share) $ 15.05 $ 13.78 $ 16.14
Outstanding at end of year 736,490 785,124 1,132,450
Outstanding at end of year (in Dollars per share) $ 14.50 $ 14.53 $ 14.30
Exercisable at end of year 736,490 785,124 1,132,450
Exercisable at end of year (in Dollars per share) $ 14.50 $ 14.53 $ 14.30