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Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details) | 3 Months Ended |
--- | --- | ---
Dec. 31, 2015 merchants Customers megawatts | Dec. 31, 2014 Customers | Sep. 30, 2015 Customers
Derivative |  |  |
Number of active future commission merchants | merchants | 2 |  |
Credit of Customers |  |  |
Derivative |  |  |
Number of customers that represent the percent of sales | 6 | 6 |
Number of customers that represent the concentration of accounts receivable percent outstanding |  |  | 3
Sales Concentration | 32.00% | 32.00% |
Percent of total outstanding accounts receivables |  |  | 27.00%
Megawatts of Power Purchase Agreement |  |  |
Derivative |  |  |
Megawatts of Power Purchase Agreement | megawatts | 440 |  |

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