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Fair Value of Derivative and Other Financial Instruments - Sale of Power (Details) | Mar. 31, 2016 $ / MWh MW
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Palo Verde Nuclear Generating Station Unit 3 [Member] | PNMR and PNM [Member] |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |
Number of megawatts nuclear generation (in megawatts) | MW | 134
Palo Verde Nuclear Generating Station Unit 3 [Member] | PNMR and PNM [Member] | Commodity Contract [Member] |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |
Derivative, average forward price (in dollars per MWh) | $ / MWh | 26
Palo Verde Nuclear Generating Station [Member] | Firm Contract [Member] | Public Service Company of New Mexico [Member] |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |
Percentage of electric power plant output sold | 100.00%

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