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Commitments and Contingencies - Nuclear Spent Fuel and Waste Disposal (Details) - Public Service Company of New Mexico - Palo Verde Nuclear Generating Station - Nuclear spent fuel and waste disposal - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Loss Contingencies [Line Items] |  |  |
Estimate of possible loss |  |  | $ 59.6
Other deferred credits |  |  |
Loss Contingencies [Line Items] |  |  |
Liability for interim storage costs | $ 13.0 | $ 12.8 |

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