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Equity method investments (Details) | 0 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Nov. 30, 2010 | Aug. 31, 2013 | Aug. 31, 2012 | Nov. 30, 2011 | Nov. 30, 2010
ECTE [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Percentage ownership interest in equity method investment sold |  |  |  |  | 59.96%
Number of years over which remaining ownership interest in equity method investment will be sold | 4 years |  |  |  |
Portion of remaining interest sold |  | 25.00% | 25.00% | 25.00% |
ENTE [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Percentage ownership interest in equity method investment sold | 100.00% |  |  |  | 100.00%
ERTE [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Percentage ownership interest in equity method investment sold | 100.00% |  |  |  | 100.00%

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- Definition Number of years over which remaining ownership interest in equity method investment will be sold. + References No definition available. + Details
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- Definition Percentage ownership interest in equity method investment sold. + References No definition available. + Details
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- Definition Amount of remaining ownership interest sold. + References No definition available. + Details
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- Details
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