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Commitments and Contingencies Commitments and Contingencies - Contingencies (Details) $ in Thousands | 12 Months Ended
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Sep. 30, 2016 USD ($) Units reactors Insurance_layers Procedures Sites | Sep. 30, 2015 USD ($) | Sep. 30, 2014 USD ($)
Contingencies |  |  |  |
Nuclear liability insurance |  | $ 375,000 |  |
Assessment from licensees for each licensed reactor |  | $ 127,000 |  |
Number of licensed reactors in US | reactors |  | 102 |  |
Nuclear accident assessment limitation per year per unit |  | $ 19,000 |  |
Number of licensed nuclear units | Units |  | 7 |  |
Maximum assessment per nuclear incident |  | $ 891,000 |  |
Maximum payment required per accident in any one year |  | 133,000 |  |
Total amount of protection available |  | $ 13,000,000 |  |
Surcharge for legal expenses |  | 5.00% |  |
Number of layers until the U.S. Congress is required to take action | Insurance_layers |  | 2 |  |
Amount of property, decommissioning, and decontamination insurance carried |  | $ 5,100,000 |  |
Amount of insurance available for loss at any one site |  | $ 2,100,000 |  |
Number of sites | Sites |  | 1 |  |
Maximum amount of retrospective premiums |  | $ 132,000 |  |
Maximum idemnity if a covered accident tasks or keeps a nuclear unit offline |  | 490,000 |  |
Maximum amount of retrospective premiums |  | 37,000 |  |
Estimated future decommissioning cost | [1] | $ 4,052,000 | $ 3,843,000 | $ 3,169,000
Number of procedures for determining estimates for the costs of nuclear decommissioning | Procedures |  | 2 |  |
Amount spent to reduce emissions since 1970 |  | $ 6,500,000 |  |
Amount spent to reduce emissions |  | 259,000 | 315,000 | 378,000
Possible additional future costs for compliance with Clean Air Act requirements |  | 375,000 |  |
Possible additional future costs for compliance with CCR requirements |  | 1,200,000 |  |
Possible additional future costs for compliance with Clean Water requirements. |  | 400,000 |  |
Amount of settlement for potential liability related to soil cleanup |  | 300 |  |
Amount of settlement for potential liability related to EPA study of site |  | 8 |  |
Remaining natural resource damages are less than |  | 0 |  |
Estimated liability for cleanup and similar environmental work on a non-discounted basis |  | 23,000 | 23,000 |
Nuclear |  |  |  |
Contingencies |  |  |  |
Estimated future decommissioning cost |  | 2,492,000 | 2,187,000 | 2,052,000
Non-nuclear |  |  |  |
Contingencies |  |  |  |
Estimated future decommissioning cost |  | $ 1,560,000 | $ 1,656,000 | $ 1,117,000
[1] | The current portions of the ARO liability in the amounts of $212 million and $161 million as of September 30, 2016 and 2015, respectively, are included in Accounts payable and accrued liabilities.

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- Definition The amount of property, decommissioning, and decontamination insurance available for loss at any one site to cover the cost of stabilizing or shutting down a reactor after an accident. + References No definition available. + Details
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- Definition The amount of property, decommissioning, and decontamination insurance carried for nuclear plants owned to cover the cost of stabilizing or shutting down a reactor after an accident. + References No definition available. + Details
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- Definition The amount of the settlement for potential liability related to soil cleanup. + References No definition available. + Details
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- Definition The amount spent to reduce emissions at power plants. + References No definition available. + Details
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- Definition The amount of settlement for potential liability related to the EPA study of site. + References No definition available. + Details
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- Definition The amount spent since 1970 to reduce emissions at power plants. + References No definition available. + Details
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- Definition An assessment from licensees for each licensed nuclear reactor in the United States to fund the second layer, the Secondary Financial Program. + References No definition available. + Details
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- Definition Maximum assessment per nuclear incident. + References No definition available. + Details
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- Definition The maximum idemnity per unit if an accident covered by the policy tasks or keeps a nuclear unit offline. + References No definition available. + Details
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- Definition The maximum payment that would be required per accident in any one year. + References No definition available. + Details
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- Definition The maximum amount of retrospective premiums that may be required for property, decommissioning, and decontamination insurance. + References No definition available. + Details
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- Definition The per year per unit limitation of the assessment for any nuclear accident + References No definition available. + Details
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- Definition For the first layer of protection all NRC nuclear plant licensees purchase nuclear insurance from American Nuclear Insurers for each nuclear plant with an operating license. + References No definition available. + Details
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- Definition The number of licensed nuclear units owned. + References No definition available. + Details
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- Definition Number of procedures for determining estimates for the costs of nuclear decommissioning + References No definition available. + Details
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- Definition The possible additional future costs for compliance with Clean Air Act requirements. + References No definition available. + Details
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- Definition The possible additional future costs for compliance with Clean Water requirements. + References No definition available. + Details
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- Definition The total amount of protection available to compensate for losses arising from a nuclear event in the United States. + References No definition available. + Details
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