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Regulatory and Rate Matters - SJGS Abandonment Application, Fours Corners, PVNGS Leased Interest Abandonment Application, Summer Peak Resource Adequacy, COVID and Transportation Electrification Program (Details) $ in Thousands |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 30, 2023 MW | Dec. 05, 2022 MW | Oct. 03, 2022 USD ($) | Sep. 08, 2022 | Jul. 29, 2022 USD ($) | Jul. 19, 2022 MW | Jun. 17, 2022 USD ($) | Apr. 02, 2021 lease MW | Jan. 08, 2021 USD ($) | Nov. 01, 2020 USD ($) | Jul. 10, 2019 proceeding | Jul. 01, 2019 USD ($) | Nov. 15, 2015 power_purchase_agreement batteryStorageAgreement numberOfAMIMeter | Nov. 30, 2020 USD ($) | Mar. 31, 2023 USD ($) MW | Dec. 31, 2021 power_purchase_agreement replacementResource | Dec. 31, 2022 USD ($) | Sep. 02, 2022 MW | Feb. 14, 2022 MW | Jul. 29, 2020 MW | Feb. 21, 2020 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in undepreciated leasehold improvements |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 88,200 |  |  |  |  |  |
Increase in deferred regulatory assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 88,200 |  |  |  |  |  |
Regulatory time frame for proposed PPAs and battery storage agreements |  |  |  |  |  |  |  | 6 months |  |  |  |  |  |  |  |  |  |  |  |  |
Number of replacement resources | replacementResource |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 933,713 |  | $ 846,686 |  |  |  |
Regulatory liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 756,561 |  | 755,202 |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 650 |
Number of megawatts in battery storage facilities (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 300 |
Filing period, extension |  |  |  | 2 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Filing period, with extension |  |  |  | 12 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for legal settlements |  |  |  |  | $ 19,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of leases under which lease term was extended | lease |  |  |  |  |  |  |  | 5 |  |  |  |  |  |  |  |  |  |  |  |  |
Potential loss on rate change |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,700 |  |  |  |  |  |
Total number of agreements | numberOfAMIMeter |  |  |  |  |  |  |  |  |  |  |  |  | 5 |  |  |  |  |  |  |  |
Number of purchase power agreements | power_purchase_agreement |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  | 3 |  |  |  |  |
Number of battery storage agreements | batteryStorageAgreement |  |  |  |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |
Number of megawatts, peak during period (in megawatts) | MW |  |  |  |  |  | 2,139 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grid modernization investment |  |  | $ 344,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grid modernization, initial term |  |  | 6 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grid modernization term |  |  | 11 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 850,860 |  | 763,941 |  |  |  |
Regulatory liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 557,564 |  | 556,989 |  |  |  |
Loss contingency |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 53,200 |  |  |  |  |  |
PNM | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reserve margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11.00% |  |  |  |  |  |
PNM | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reserve margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16.00% |  |  |  |  |  |
PNM | Four Corners |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Request issuance of energy transition bonds |  |  |  |  |  |  |  |  | $ 300,000 |  |  |  |  |  |  |  |  |  |  |  |
Forecasted undepreciated investment |  |  |  |  |  |  |  |  | 272,000 |  |  |  |  |  |  |  |  |  |  |  |
Plant decommissioning and coal mine reclamation costs |  |  |  |  |  |  |  |  | 4,600 |  |  |  |  |  |  |  |  |  |  |  |
Upfront financing costs |  |  |  |  |  |  |  |  | 7,300 |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from securitization bonds |  |  |  |  |  |  |  |  | $ 16,500 |  |  |  |  |  |  |  |  |  |  |  |
Payments for relief from obligations |  |  |  |  |  |  |  |  |  | $ 75,000 |  |  |  | $ 15,000 |  |  |  |  |  |  |
Final payment for relief from obligations |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 60,000 |  |  |  |  |  |  |
PNM | Four Corners | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Noncontrolling interest, ownership percentage by noncontrolling owners |  |  |  |  |  |  |  |  |  | 13.00% |  |  |  |  |  |  |  |  |  |  |
PNM | Deferred COVID-19 Costs | COVID-19 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,700 |  |  |  |  |  |
Regulatory liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 900 |  | $ 900 |  |  |  |
PNM | Leased Interest Termination on January 15, 2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of leases under which lease term was extended | lease |  |  |  |  |  |  |  | 4 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Leased Interest Termination on January 15, 2023 | NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  | 104 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Leased Interest Termination on January 15, 2024 | NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  | 10 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Replacement Resource Portfolio One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  | 150 |  |  |  |  |  |  |  |  |  |  | 150 |  |
Number of megawatts in battery storage facilities (in megawatts) | MW |  |  |  |  |  |  |  | 40 |  |  |  |  |  |  |  |  |  |  | 40 |  |
PNM | Replacement Resource Portfolio Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) | MW |  |  |  |  |  |  |  | 100 |  |  |  |  |  |  |  |  |  |  | 100 |  |
PNM | Replacement Resource Portfolio Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  | 300 |  |  |  |  |  |  |  |  |  |  | 300 |  |
Number of megawatts in battery storage facilities (in megawatts) | MW |  |  |  |  |  |  |  | 150 |  |  |  |  |  |  |  |  |  | 300 | 150 |  |
PNM | Solar Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW | 100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Battery Storage Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW | 30 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | NM 2022 Rate Case |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Megawatt repurchase | MW |  | 64.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Firm Power Purchases |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 420 |  |  |  |  |  |
PNM | Firm Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40 |  |  |  |  |  |
San Juan Generating Station | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Request issuance of energy transition bonds |  |  |  |  |  |  |  |  |  |  |  | $ 361,000 |  |  |  |  |  |  |  |  |
Forecasted undepreciated investment |  |  |  |  |  |  |  |  |  |  |  | 283,000 |  |  |  |  |  |  |  |  | $ 361,000
Plant decommissioning and coal mine reclamation costs |  |  |  |  |  |  |  |  |  |  |  | 28,600 |  |  |  |  |  |  |  |  |
Upfront financing costs |  |  |  |  |  |  |  |  |  |  |  | 9,600 |  |  |  |  |  |  |  |  |
Severance costs |  |  |  |  |  |  |  |  |  |  |  | 20,000 |  |  |  |  |  |  |  |  |
Proceeds from securitization bonds |  |  |  |  |  |  |  |  |  |  |  | $ 19,800 |  |  |  |  |  |  |  |  |
Number of proceedings | proceeding |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |
Number of recommendations | proceeding |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |
San Juan Generation Station, Unit 1 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual rate credits |  |  |  |  |  |  | $ 21,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |
San Juan Generating Station, Unit 4 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual rate credits |  |  |  |  |  |  | $ 98,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of days to transfer payment |  |  |  |  |  |  | 30 days |  |  |  |  |  |  |  |  |  |  |  |  |  |

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