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Fair Value of Derivative and Other Financial Instruments - Defined Benefit Plans Disclosure (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
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Public Service Company of New Mexico | Pension Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | $ 576,707 | $ 587,530 | $ 531,467
Public Service Company of New Mexico | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 95,805 | 93,402 | 86,400
Public Service Company of New Mexico | Fair Value, Inputs, Level 1, 2 and 3 | Pension Plan | Participation in PNMR Master Trust Investments: | Fair Value Measurement [Domain] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 527,873 | 498,907 |
Public Service Company of New Mexico | Fair Value, Inputs, Level 1, 2 and 3 | Pension Plan | Participation in PNMR Master Trust Investments: |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 577,305 | 587,891 |
Public Service Company of New Mexico | Fair Value, Inputs, Level 1, 2 and 3 | Pension Plan | Participation in PNMR Master Trust Investments: | Estimate of Fair Value Measurement |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 49,432 | 88,984 |
Public Service Company of New Mexico | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 96,127 | 93,710 |
Public Service Company of New Mexico | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 1,578 | 1,310 |
Public Service Company of New Mexico | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 94,549 | 92,400 |
Public Service Company of New Mexico | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Plan | Participation in PNMR Master Trust Investments: |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 235,605 | 241,445 |
Public Service Company of New Mexico | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 59,961 | 53,594 |
Public Service Company of New Mexico | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Postretirement Benefits | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 1,578 | 1,310 |
Public Service Company of New Mexico | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Postretirement Benefits | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 58,383 | 52,284 |
Public Service Company of New Mexico | Significant Other Observable Inputs (Level 2) | Pension Plan | Participation in PNMR Master Trust Investments: |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 292,268 | 257,462 |
Public Service Company of New Mexico | Significant Other Observable Inputs (Level 2) | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 36,166 | 40,116 |
Public Service Company of New Mexico | Significant Other Observable Inputs (Level 2) | Other Postretirement Benefits | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
Public Service Company of New Mexico | Significant Other Observable Inputs (Level 2) | Other Postretirement Benefits | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 36,166 | 40,116 |
Texas-New Mexico Power Company | Pension Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 62,942 | 66,149 | 59,367
Texas-New Mexico Power Company | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 12,593 | 12,885 | $ 10,844
Texas-New Mexico Power Company | Fair Value, Inputs, Level 1, 2 and 3 | Pension Plan | Participation in PNMR Master Trust Investments: | Fair Value Measurement [Domain] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 58,623 | 56,966 |
Texas-New Mexico Power Company | Fair Value, Inputs, Level 1, 2 and 3 | Pension Plan | Participation in PNMR Master Trust Investments: |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 62,585 | 66,196 |
Texas-New Mexico Power Company | Fair Value, Inputs, Level 1, 2 and 3 | Pension Plan | Participation in PNMR Master Trust Investments: | Estimate of Fair Value Measurement |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 3,962 | 9,230 |
Texas-New Mexico Power Company | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 12,630 | 12,861 |
Texas-New Mexico Power Company | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 381 | 18 |
Texas-New Mexico Power Company | Fair Value, Inputs, Level 1, 2 and 3 | Other Postretirement Benefits | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 12,249 | 12,843 |
Texas-New Mexico Power Company | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Plan | Participation in PNMR Master Trust Investments: |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 21,390 | 28,732 |
Texas-New Mexico Power Company | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 11,956 | 10,824 |
Texas-New Mexico Power Company | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Postretirement Benefits | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 381 | 18 |
Texas-New Mexico Power Company | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Postretirement Benefits | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 11,575 | 10,806 |
Texas-New Mexico Power Company | Significant Other Observable Inputs (Level 2) | Pension Plan | Participation in PNMR Master Trust Investments: |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 37,233 | 28,234 |
Texas-New Mexico Power Company | Significant Other Observable Inputs (Level 2) | Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 674 | 2,037 |
Texas-New Mexico Power Company | Significant Other Observable Inputs (Level 2) | Other Postretirement Benefits | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
Texas-New Mexico Power Company | Significant Other Observable Inputs (Level 2) | Other Postretirement Benefits | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 674 | 2,037 |
PNMR |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | $ 639,890 | $ 654,087 |
PNMR | Private equity funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] | Fair Value Measured at Net Asset Value Per Share | Fair Value Measured at Net Asset Value Per Share |
PNMR | Hedge funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] | Fair Value Measured at Net Asset Value Per Share | Fair Value Measured at Net Asset Value Per Share |
PNMR | Real estate funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] | Fair Value Measured at Net Asset Value Per Share | Fair Value Measured at Net Asset Value Per Share |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | $ 586,496 | $ 555,873 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 18,924 | 20,812 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | Corporate stocks, common |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 92,484 | 114,983 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | Corporate stocks, preferred |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 806 | 1,187 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 222,106 | 173,931 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | U.S. government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 95,429 | 97,460 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | International government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 5,977 | 6,202 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | Municipals |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 6,143 | 6,277 |
PNMR | Fair Value, Inputs, Level 1, 2 and 3 | Corporate and other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 144,627 | 135,021 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 256,995 | 270,177 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 18,924 | 20,812 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate stocks, common |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 92,484 | 114,983 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate stocks, preferred |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 135 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 59,203 | 47,418 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 86,384 | 86,829 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | International government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipals |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
PNMR | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate and other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
PNMR | Significant Other Observable Inputs (Level 2) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 329,501 | 285,696 |
PNMR | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
PNMR | Significant Other Observable Inputs (Level 2) | Corporate stocks, common |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 0 | 0 |
PNMR | Significant Other Observable Inputs (Level 2) | Corporate stocks, preferred |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 806 | 1,052 |
PNMR | Significant Other Observable Inputs (Level 2) | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 162,903 | 126,513 |
PNMR | Significant Other Observable Inputs (Level 2) | U.S. government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 9,045 | 10,631 |
PNMR | Significant Other Observable Inputs (Level 2) | International government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 5,977 | 6,202 |
PNMR | Significant Other Observable Inputs (Level 2) | Municipals |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 6,143 | 6,277 |
PNMR | Significant Other Observable Inputs (Level 2) | Corporate and other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 144,627 | 135,021 |
PNMR | Fair Value Measured at Net Asset Value Per Share | Private equity funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 10,479 | 12,552 |
PNMR | Fair Value Measured at Net Asset Value Per Share | Hedge funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | 8,913 | 52,285 |
PNMR | Fair Value Measured at Net Asset Value Per Share | Real estate funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets, amount | $ 34,002 | $ 33,377 |

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