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Fair Value of Derivative and Other Financial Instruments - Sale of Power (Details)	Mar. 31, 2016 $ / MWh MW
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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- Definition

Percentage of Electric Power Plant Output Sold for 2014 and 2015

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Public Utilities, Number of Megawatts Nuclear Generation

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- Definition

The average forward price on the group of price risk forward or futures contracts, such as gas futures contracts.

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