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Regulatory and Rate Matters - SJGS Abandonment Application (Details) $ in Thousands |  |  |  |  |  | 9 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 02, 2020 USD ($) | Apr. 01, 2020 USD ($) | Jul. 10, 2019 | Jul. 01, 2019 USD ($) scenario MW | May 31, 2019 MW | Sep. 30, 2020 USD ($) MW | Sep. 30, 2019 USD ($) | Sep. 28, 2020 USD ($) MW | Jun. 24, 2020 MW | Mar. 31, 2020 USD ($) | Mar. 27, 2020 MMBTU MW | Feb. 21, 2020 USD ($) | Aug. 10, 2018 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in allowance for equity funds used during construction | $ |  |  |  |  |  | $ 6,728 | $ 6,714 |  |  |  |  |  |
NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Deadline extension period to issue abandonment and financing order |  |  | 9 months |  |  |  |  |  |  |  |  |  |
Deadline extension period to issue replacement resources order |  |  | 15 months |  |  |  |  |  |  |  |  |  |
COVID-19 |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred incremental costs | $ |  |  |  |  |  | $ 3,600 |  |  |  |  |  |  |
PNM Solar Direct |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  | 50 |  |  |  |  |  |  |  |
Power purchase agreement term |  |  |  |  | 15 years |  |  |  |  |  |  |  |
Replacement Resource Portfolio Two | Hearing Examiners Approach Two |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts for natural gas facility (in Megawatts) |  |  |  |  |  |  |  |  | 200 |  |  |  |
Replacement Resource Portfolio Four | Hearing Examiners Approach One |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts for demand response (in Megawatts) |  |  |  |  |  |  |  |  | 24 |  |  |  |
KV Transmission Line |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated cost of project | $ |  |  |  |  |  |  |  |  |  |  |  |  | $ 85,000
KV Transmission Line | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated cost of project | $ | $ 109,000 |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in estimated cost of project | $ | $ 24,000 |  |  |  |  |  |  |  |  |  |  |  |
Required Percentage by 2020 | Energy Transition Act | Electric-Generation Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy, percentage |  |  |  |  |  | 0.20 |  |  |  |  |  |  |
Required Percentage by 2025 | Energy Transition Act | Electric-Generation Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy, percentage |  |  |  |  |  | 0.40 |  |  |  |  |  |  |
Required Percentage by 2030 | Energy Transition Act | Electric-Generation Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy, percentage |  |  |  |  |  | 0.50 |  |  |  |  |  |  |
Required Percentage by 2040 | Energy Transition Act | Electric-Generation Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy, percentage |  |  |  |  |  | 0.80 |  |  |  |  |  |  |
Required Percentage by 2045 | Energy Transition Act | Electric-Generation Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy, percentage |  |  |  |  |  | 1 |  |  |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  |  |  |  | 40 |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  |  |  |  | 300 |  |
Solar generation capacity, power purchase agreements (in Megawatts) | MMBTU |  |  |  |  |  |  |  |  |  |  | 20 |  |
Increase (decrease) in allowance for equity funds used during construction | $ |  |  |  |  |  | $ 4,229 | $ 4,904 |  |  |  |  |  |
PNM | Audit Of PNM’s Compliance With OATT And Financial Reporting |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest expense, debt | $ |  |  |  |  |  | 1,900 |  |  |  |  |  |  |
Increase (decrease) in allowance for equity funds used during construction | $ |  |  |  |  |  | $ 100 |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  | 145.0 |  |  |  |  |  |  |
PNM | PNM Solar Direct |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  |  |  |  | 50 |  |
PNM | Replacement Resource Portfolio One | Hearing Examiners Approach One |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  |  | 150 |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  |  | 300 |  |  |  |
PNM | Replacement Resource Portfolio Two | Hearing Examiners Approach One |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  |  | 20 |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  |  | 50 |  |  |  |
PNM | Replacement Resource Portfolio Three |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  | 100 |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  | 200 |  |  |  |  |
PNM | Replacement Resource Portfolio Three | Hearing Examiners Approach One |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  |  | 100 |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  |  | 200 |  |  |  |
PNM | Replacement Resource Portfolio Four |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  | 30 |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  | 100 |  |  |  |  |
PNM | Replacement Resource Portfolio Four | Hearing Examiners Approach One |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  |  | 30 |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  |  | 100 |  |  |  |
PNM | Replacement Resource Portfolio Five |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  |  |  |  |  | 130 |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  |  |  |  |  | 299 |  |  |  |  |
PNM | Required Percentage by 2011 | Renewable Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  | 10.00% |  |  |  |  |  |  |
PNM | Required Percentage by 2015 | Renewable Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  | 15.00% |  |  |  |  |  |  |
PNM | Required Percentage by 2020 | Renewable Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  | 20.00% |  |  |  |  |  |  |
San Juan Generating Station |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated costs of replacement resources | $ |  |  |  |  |  |  |  | $ 8,100 |  |  |  |  |
San Juan Generating Station | Other deferred credits |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring reserve | $ |  |  |  |  |  | $ 38,100 |  |  |  |  |  |  |
San Juan Generating Station | Employee Severance |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring reserve | $ |  |  |  |  |  |  |  |  |  | $ 9,400 |  |  |
San Juan Generating Station | PNM |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts in natural gas-fired peaking plant (in megawatts) |  |  |  | 280 |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities (in megawatts) |  |  |  | 70 |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) |  |  |  | 350 |  |  |  |  |  |  |  |  |
Number of megawatts in battery storage facilities, replacement resource scenario (in megawatts) |  |  |  | 60 |  |  |  |  |  |  |  |  |
Number of replacement resource scenarios | scenario |  |  |  | 3 |  |  |  |  |  |  |  |  |
Request issuance of energy transition bonds | $ |  | $ 361,000 |  | $ 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 |  |  |  |  |  |  |  |  |
San Juan Generating Station | PNM | Other deferred credits |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring reserve | $ |  |  |  |  |  | $ 36,800 |  |  |  |  |  |  |
San Juan Generating Station | PNM | Employee Severance |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring reserve | $ |  |  |  |  |  |  |  |  |  | 8,100 |  |  |
San Juan Generating Station | PNM | Other Restructuring |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring reserve | $ |  |  |  |  |  |  |  |  |  | 8,900 |  |  |
San Juan Generating Station | PNM | Economic Development and Workforce Training Costs |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring reserve | $ |  |  |  |  |  |  |  |  |  | $ 19,800 |  |  |

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