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Commitments and Contingencies - The Clean Air Act (Details) |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |  |  |  |
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Feb. 25, 2016 | Dec. 31, 2015 USD ($) | Dec. 16, 2015 USD ($) MWh MW | Jul. 31, 2015 USD ($) MW | Mar. 02, 2015 lb / MMBTU T | Dec. 31, 2015 USD ($) | Sep. 30, 2017 USD ($) lbsofnox / mmbtu joint_owner requirement MW | Dec. 31, 2016 USD ($) | Sep. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Sep. 30, 2017 USD ($) lbsofnox / mmbtu joint_owner requirement MW | Sep. 30, 2016 USD ($) | Dec. 31, 2016 USD ($) | Jan. 26, 2016 state | Oct. 01, 2015 parts_per_billion | Sep. 30, 2015 parts_per_billion | May 14, 2015 lb / MMBTU | Dec. 30, 2013 | Apr. 30, 2013 well | Feb. 28, 2013 lawsuit state mine | Aug. 06, 2012 compliance_alternative | Jan. 31, 2010 parts_per_billion | Jul. 31, 2005 T | Dec. 31, 1999 state
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  |  |  |  |  |  | $ 0 |  | $ 16,451,000 |  | $ 0 | $ 17,225,000 |  |  |  |  |  |  |  |  |  |  |  |
Plant in service, held for future use, and to be abandoned |  |  |  |  |  |  | 7,133,646,000 | $ 6,944,534,000 |  |  | 7,133,646,000 |  | $ 6,944,534,000 |  |  |  |  |  |  |  |  |  |  |
Accumulated depreciation and amortization |  |  |  |  |  |  | $ 2,431,695,000 | 2,334,938,000 |  |  | $ 2,431,695,000 |  | 2,334,938,000 |  |  |  |  |  |  |  |  |  |  |
Clean Air Act related to regional haze |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of states to address regional haze (in states) | state |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50
Potential to emit tons per year of visibility impairing pollution (in tons, more than) | T |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 250 |
Clean Power Plan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of potential extension to meet environmental targets |  |  |  |  |  |  |  |  |  |  | 2 years |  |  |  |  |  |  |  |  |  |  |  |  |
Number of states that filed a petition against the Clean Power Plan | state |  |  |  |  |  |  |  |  |  |  |  |  |  | 29 |  |  |  |  |  |  |  |  |  |
San Juan Generating Station Unit 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of other joint owners | joint_owner |  |  |  |  |  |  | 8 |  |  |  | 8 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  |  |  |  |  |  | $ 0 |  | 16,451,000 |  | $ 0 | $ 17,225,000 |  |  |  |  |  |  |  |  |  |  |  |
Plant in service, held for future use, and to be abandoned |  |  |  |  |  |  | 5,463,764,000 | 5,359,211,000 |  |  | 5,463,764,000 |  | 5,359,211,000 |  |  |  |  |  |  |  |  |  |  |
Accumulated depreciation and amortization |  |  |  |  |  |  | $ 1,881,371,000 | 1,809,528,000 |  |  | $ 1,881,371,000 |  | 1,809,528,000 |  |  |  |  |  |  |  |  |  |  |
Power to be sold to third party (in megawatts) | MW |  |  |  |  |  |  | 36 |  |  |  | 36 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated costs to remain unrecovered |  |  | $ 20,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Increase in coal mine decommissioning liability |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expense reflected in regulatory disallowances and restructuring costs |  |  |  |  |  |  |  |  | 4,800,000 |  |  |  | 4,500,000 |  |  |  |  |  |  |  |  |  |  |
PNM | National Ambient Air Quality Standards, 2015 EPA Legal Settlement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time to act on settlement |  |  |  |  | 16 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Emissions tons of SO2 per year (more than) | T |  |  |  |  | 16,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | National Ambient Air Quality Standards, 2015 EPA Legal Settlement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time from state designation, to provide implementation plans | 36 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | WEG v OSM lawsuit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of mines impacted | mine |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7 |  |  |  |
Number of states impacted | state |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  |  |  |
Number of claims for relief, filed (in lawsuits) | lawsuit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 |  |  |  |
PNM | Santa Fe generating station |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of wells with elevated levels of nitrates | well |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |
PNM | San Juan Generating Station Units 2 and 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Plant in service, held for future use, and to be abandoned |  |  |  |  |  |  | $ 471,800,000 |  |  |  | $ 471,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated depreciation and amortization |  |  |  |  |  |  | 211,600,000 |  |  |  | 211,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Net book value |  |  |  |  |  |  | $ 260,200,000 |  |  |  | $ 260,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Units 2 and 3 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current ownership interest (in megawatts) | MW |  |  | 418 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Time period to recover retired units' remaining net book value |  |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recovery percentage of estimated undepreciated value at 12/31/17 |  | 50.00% | 50.00% |  |  | 50.00% | 50.00% |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  | $ 127,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expense reflected in regulatory disallowances and restructuring costs |  |  |  |  |  |  |  | $ (2,300,000) | $ 5,200,000 | $ 800,000 |  |  | $ 3,700,000 |  |  |  |  |  |  |  |  |  |  |
Accumulated plant write-off, disallowance |  |  |  |  |  |  | $ 128,600,000 |  |  |  | $ 128,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Net carrying value of utility plant |  |  |  |  |  |  | $ 131,600,000 |  |  |  | $ 131,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station | WEG v OSM lawsuit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of claims for relief, filed (in lawsuits) | lawsuit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |
PNM | San Juan Generating Station Unit 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional ownership to be obtained (in megawatts) | MW |  |  | 65 | 132 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated rate base value |  |  | $ 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Coal-fired generation (in megawatts) | MW |  |  | 197 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatt hours of Renewable Energy Certificates to be acquired and retired (in megawatt hours) | MWh |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership held by exiting owners |  |  |  |  |  |  | 38.80% |  |  |  | 38.80% |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  | 38.50% |  |  |  | 38.50% |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Unit 4 | Clean Air Act, Post-2022 coal supply future rate case |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time agreed to by all parties to settle rate case |  |  | 6 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Unit 4 | Clean Air Act, SNCR Hearing Examiner, Recommended Denial |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional ownership to be obtained (in megawatts) | MW |  |  | 132 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Unit 3 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership held by exiting owners |  |  |  |  |  |  | 50.00% |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  | 50.00% |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Palo Verde Nuclear Generating Station Unit 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts nuclear generation (in megawatts) | MW |  |  |  |  |  |  | 134 |  |  |  | 134 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Palo Verde Nuclear Generating Station Unit 3 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts nuclear generation (in megawatts) | MW |  |  | 134 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated undepreciated value at 12/31/17 |  |  | $ 155,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Four Corners | Clean Air Act related to post combustion controls |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of compliance alternatives | compliance_alternative |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |
Plant requirement to meet NOx emissions limit (in pounds of NOx per MMBTU) | lbsofnox / mmbtu |  |  |  |  |  |  | 0.015 |  |  |  | 0.015 |  |  |  |  |  |  |  |  |  |  |  |  |
Plant requirement to meet opacity limit |  |  |  |  |  |  | 20.00% |  |  |  | 20.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Rule imposes opacity limitation on certain fugitive dust emissions from coal and material handling operations |  |  |  |  |  |  | 20.00% |  |  |  | 20.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Estimate of possible loss |  |  |  |  |  |  | $ 89,200,000 |  |  |  | $ 89,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Four Corners Units 4 and 5 (Coal) | Clean Air Act related to post combustion controls |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  | 13.00% |  |  |  | 13.00% |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Four Corners Units 1, 2 and 3 (Coal) | Clean Air Act related to post combustion controls |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.00% |  |  |  |  |  |
PNM | Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other Costs | San Juan Generating Station Units 1 and 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Installation costs |  |  |  |  |  | $ 77,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNMR Development | San Juan Generating Station Unit 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional ownership to be obtained (in megawatts) | MW |  |  |  | 65 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expense reflected in regulatory disallowances and restructuring costs |  |  |  |  |  |  |  |  |  | $ 600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential acquisition of ownership (in megawatts) | MW |  |  |  | 65 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | PNM | San Juan Generating Station Unit 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual cost of Renewable Energy Credits |  |  | $ 7,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | PNM | San Juan Generating Station and Four Corners |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposed government standard emission limit (in ozone parts per million) | parts_per_billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 70 |  |
Government standard emission limit (in ozone parts per million) | parts_per_billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 70 | 75 |  |  |  |  |  |  |  |
Minimum | PNM | National Ambient Air Quality Standards, 2015 EPA Legal Settlement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Emissions tons of SO2 per year (more than) | T |  |  |  |  | 2,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
One-hour SO2 emissions rate (in pounds per MMBTU) | lb / MMBTU |  |  |  |  | 0.45 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum | PNM | San Juan Generating Station and Four Corners |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposed government standard emission limit (in ozone parts per million) | parts_per_billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 60 |  |
Increase in coal mine decommissioning liability | PNM | San Juan Generating Station Units 2 and 3 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  | 165,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surface | Loss on long-term purchase commitment | PNM | San Juan Generating Station |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  | $ 16,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimate of possible loss |  |  |  |  |  |  | $ 100,900,000 |  |  |  | $ 100,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Energy equipment | PNMR Development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Costs of installing equipment |  |  |  | $ 7,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Plan | PNM | San Juan Generating Station Units 1 and 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  | 66.30% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Plan | PNM | San Juan Generating Station Unit 4 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  | 77.30% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
San Juan Generating Station | PNM | National Ambient Air Quality Standards |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revised SO2 emissions (in pounds per MMBTU) | lb / MMBTU |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.10 |  |  |  |  |  |  |
Reeves Station | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requirements to be implemented | requirement |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |  |  |

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