XML 79 R62.htm IDEA: XBRL DOCUMENT
v3.20.2

Regulatory and Rate Matters - PNM (Details) |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 14, 2020 | Jun. 01, 2020 USD ($) | May 28, 2020 USD ($) | Apr. 15, 2020 USD ($) MMBTU meter | Feb. 01, 2018 | Jan. 10, 2018 USD ($) | Jul. 03, 2017 | Dec. 07, 2016 USD ($) | Sep. 28, 2016 USD ($) lease MW | Aug. 27, 2015 USD ($) | Aug. 31, 2016 USD ($) lease MW | Sep. 30, 2020 USD ($) MW | Sep. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Jun. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) MW | Sep. 30, 2019 USD ($) | Dec. 31, 2019 USD ($) GWh | Dec. 31, 2017 | Mar. 27, 2020 MW | May 16, 2019 MW | Sep. 30, 2016 MW | Jan. 31, 2016 MW
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income taxes (benefit) |  |  |  |  |  |  |  |  |  |  |  | $ (12,331,000) | $ (9,188,000) |  |  | $ (14,726,000) | $ 32,420,000 |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  |  |  |  |  |  |  |  |  |  |  | $ 0 | 0 |  |  | $ 0 | 150,599,000 |  |  |  |  |  |
Percent of non-fuel revenue requirement change implemented |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Excess return on jurisdictional equity that would require refund |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  |  |  | 0.50% |  |  |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income taxes (benefit) |  |  |  |  |  |  |  |  |  |  |  | $ (13,591,000) | (9,525,000) |  |  | $ (16,127,000) | 31,984,000 |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  |  |  |  |  |  |  |  |  |  |  | $ 0 | $ 0 |  |  | $ 0 | 150,599,000 |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 300 |  |  |
Action plan, covered period |  |  |  |  |  |  | 4 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2015 Electric Rate Case | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  |  |  |  |  | $ 123,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) of non-fuel revenue |  |  |  |  |  |  |  |  |  | $ 121,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Approved rate increase (decrease) |  |  |  |  |  |  |  |  | $ 61,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts of Solar PV facilities | MW |  |  |  |  |  |  |  |  |  |  |  | 157 |  |  |  | 157 |  |  |  |  |  |  |
Current output in the geothermal facility (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  | 15 |  |  |  | 15 |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  | 145.0 |  |  |  | 145.0 |  |  |  |  |  |  |
Energy Efficiency and Load Management Program | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Energy efficiency and load management programs targeted energy savings (in Gigawatts) | MMBTU |  |  |  | 80 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program costs related to energy efficiency, in year two |  |  |  | $ 31,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program costs related to energy efficiency, in year three |  |  |  | 31,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program costs related to energy efficiency, in year four |  |  |  | $ 29,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of AMI meters to be installed | meter |  |  |  | 5,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program costs related to meter installation |  |  |  | $ 2,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Integrated Resource Plan, 2011 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Frequency of IRP filings |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |
Planning period covered of IRP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20 years |  |  |  |  |  |  |
Integrated Resource Plan, 2017 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Planning period covered of IRP |  |  |  |  |  |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Integrated Resource Plan, 2020 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Planning period covered of IRP |  |  |  |  |  |  |  |  |  |  |  |  | 20 years |  |  |  |  |  |  |  |  |  |
NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  |  |  | $ 99,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested return on equity |  |  |  |  |  |  |  | 10.125% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time for proposed return to customers the benefit of the reduction in New Mexico's corporate income tax rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |
Action plan, covered period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years |  |  |  |  |  |  |
NMPRC | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  | $ 10,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested return on equity |  |  |  |  |  | 9.575% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time for proposed return to customers the benefit of the reduction in New Mexico's corporate income tax rate |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposed revision to rider that will allow for recovery |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 49,600,000 |  |  |  |  |
NMPRC | Renewable Energy Rider | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposed revision to rider that will allow for recovery |  | $ 67,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue from renewable energy rider, year two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 58,900,000 |  |  |  |  |  |  |
Recorded revenues from renewable rider |  |  |  |  |  |  |  |  |  |  |  | $ 12,000,000.0 | $ 11,900,000 |  |  | $ 42,300,000 | $ 37,400,000 |  |  |  |  |  |
NMPRC | Renewable Energy Rider, Sky Blue Energy Program | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposed revision to rider that will allow for recovery |  | $ 2,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy procurement plan, carrying charges, percent |  | 8.64% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy procurement plant, carrying charges |  | $ 700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
NMPRC | Renewable Energy Rider, Sky Blue Energy Program | PNM | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable energy procurement plan, carrying charges, percent | 4.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required Percentage by 2011 | Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  | 10.00% |  |  |  |  |  |  |
Required Percentage by 2015 | Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  |  |  |  |  |  |  | 15.00% |  |  |  | 15.00% |  |  |  |  |  |  |
Required Percentage by 2020 | Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  |  |  |  |  |  |  | 20.00% |  |  |  | 20.00% |  |  |  |  |  |  |
Minimum | Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Profit incentive sliding scale multiplier |  |  |  | 0.071 |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.071 |  |  |  |  |
Energy efficiency and load management programs targeted energy savings (in Gigawatts) | MMBTU |  |  |  | 80 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reasonable cost threshold in megawatts per hour |  |  |  |  |  |  |  |  |  |  |  | $ 60 |  |  |  | $ 60 |  |  |  |  |  |  |
Palo Verde Nuclear Generating Station, Unit 2 Leases | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts purchased (in megawatts) | MW |  |  |  |  |  |  |  |  | 64.1 |  | 64.1 |  |  |  |  |  |  |  |  |  |  | 64.1 | 64.1
Number of megawatts nuclear generation (in megawatts) | MW |  |  |  |  |  |  |  |  | 114.6 |  | 114.6 |  |  |  |  |  |  |  |  |  | 114.6 | 114.6 |
Number of leases under which assets were purchased | lease |  |  |  |  |  |  |  |  | 3 |  | 3 |  |  |  |  |  |  |  |  |  |  |  |
Public utilities, aggregate annual rent expense |  |  |  |  |  |  |  |  |  |  | $ 18,100,000 |  |  |  |  |  |  |  |  |  |  |  |
Palo Verde Nuclear Generating Station, Unit 2 Leases | 2015 Electric Rate Case | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hearing examiner's proposed disallowance of recovery |  |  |  |  |  |  |  |  |  |  | $ 163,300,000 |  |  |  |  |  |  |  |  |  |  |  |
Initial rate base value |  |  |  |  |  |  |  |  | $ 83,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disallowance of the recovery undepreciated costs of capitalized leasehold improvements |  |  |  |  |  |  |  |  | $ 43,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pre-tax regulatory disallowance |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 19,700,000 |  |  |  |  |  |  |  |  |
New Mexico Wind | Renewable Portfolio Standard 2014 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts for wind energy | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 204 |  |  |  |  |  |  |
Red Mesa Wind | Renewable Portfolio Standard 2014 | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts for wind energy | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 102 |  |  |  |  |  |  |
La Joya Wind | Renewable Portfolio Standard | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts for wind energy | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 140 |  |  |  |  |  |  |
Four Corners |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowances and restructuring costs |  |  |  |  |  | $ 47,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowance |  |  |  |  |  | $ 148,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
New Mexico 2015 Rate Case | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pre-tax impairment of investments |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,300,000 | $ 150,600,000 |  |  |  |  |  |  |  |
Undepreciated capitalized improvements |  |  |  |  |  |  |  |  |  |  |  | $ 39,700,000 |  |  |  | $ 39,700,000 |  |  |  |  |  |  |
New Mexico 2015 Rate Case | Palo Verde Nuclear Generating Station, Unit 2 Leases | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts purchased (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  | 64.1 |  |  |  | 64.1 |  |  |  |  | 64.1 |  |
Portion of purchase price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 73,200,000 |  |  |  |  |  |  |
Income taxes (benefit) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 45,700,000 |  |  |  |  |  |  |
New Mexico 2015 Rate Case | Palo Verde Nuclear Generating Station, Unit 1 and 4 Leases | PNM | Leaseholds and Leasehold Improvements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Undepreciated capitalized improvements |  |  |  |  |  |  |  |  |  |  |  | $ 37,700,000 |  |  |  | $ 37,700,000 |  |  |  |  |  |  |
Disincentives and Incentives Added | 2017 Energy Efficiency and Load Management Program | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Energy efficiency and load management programs profit incentive, minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,800,000 |  |  |  |  |
Energy efficiency and load management programs targeted energy savings (in Gigawatts) | GWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 59 |  |  |  |  |
Energy efficiency and load management programs additional incentive targeted energy savings (in Gigawatts) | GWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 68 |  |  |  |  |
Disincentives and Incentives Added | 2019 Energy Efficiency and Load Management Program | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Energy efficiency and load management programs profit incentive, minimum |  |  | $ 500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition Number of Mega Watts Purchased + References No definition available. + Details
Name: | pnm_NumberOfMegaWattsPurchased
Namespace Prefix: | pnm_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Operating Lease, Annual Rent Expense + References No definition available. + Details
Name: | pnm_OperatingLeaseAnnualRentExpense
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Approved lease acquisition costs + References No definition available. + Details
Name: | pnm_PublicUtilitiesApprovedleaseacquisitioncosts
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Public Utilities, Commitments And Contingencies [Line Items] + References No definition available. + Details
Name: | pnm_PublicUtilitiesCommitmentsAndContingenciesLineItems
Namespace Prefix: | pnm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Disallowed leasehold improvements + References No definition available. + Details
Name: | pnm_PublicUtilitiesDisallowedleaseholdimprovements
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Energy Efficiency and Load Management Programs Additional Incentive Targeted Energy Savings + References No definition available. + Details
Name: | pnm_PublicUtilitiesEnergyEfficiencyAndLoadManagementProgramsAdditionalIncentiveTargetedEnergySavings
Namespace Prefix: | pnm_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Energy Efficiency and Load Management Programs Profit Incentive, Minimum + References No definition available. + Details
Name: | pnm_PublicUtilitiesEnergyEfficiencyAndLoadManagementProgramsProfitIncentiveMinimum
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Energy Efficiency and Load Management Programs Targeted Energy Savings + References No definition available. + Details
Name: | pnm_PublicUtilitiesEnergyEfficiencyAndLoadManagementProgramsTargetedEnergySavings
Namespace Prefix: | pnm_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Frequency of IRP filings + References No definition available. + Details
Name: | pnm_PublicUtilitiesFrequencyofIRPfilings
Namespace Prefix: | pnm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Hearing Examiner Proposed disallowance, Lease Acquisition costs + References No definition available. + Details
Name: | pnm_PublicUtilitiesHearingExaminerProposeddisallowanceLeaseAcquisitioncosts
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Integrated Resource Plan, Action Plan, Period + References No definition available. + Details
Name: | pnm_PublicUtilitiesIntegratedResourcePlanActionPlanPeriod
Namespace Prefix: | pnm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Number Of AMI Meters To Be Installed + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberOfAMIMetersToBeInstalled
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Number of Mega Watts of Solar Photovoltaic Capacity + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberOfMegaWattsOfSolarPhotovoltaicCapacity
Namespace Prefix: | pnm_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Number of Mega Watts of Solar Photovoltaic Capacity, Current Output + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberofMegaWattsofSolarPhotovoltaicCapacityCurrentOutput
Namespace Prefix: | pnm_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Number of Mega Watts of Wind Energy Capacity + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberofMegaWattsofWindEnergyCapacity
Namespace Prefix: | pnm_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Number of Megawatts Nuclear Generation + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberofMegawattsNuclearGeneration
Namespace Prefix: | pnm_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Number of leases under which assets were purchased + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberofleasesunderwhichassetswerepurchased
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Percent of Non-fuel Revenue Requirement Change Implemented + References No definition available. + Details
Name: | pnm_PublicUtilitiesPercentofNonfuelRevenueRequirementChangeImplemented
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Planning Period Covered of IRP + References No definition available. + Details
Name: | pnm_PublicUtilitiesPlanningPeriodCoveredOfIrp
Namespace Prefix: | pnm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Profit Incentive Sliding Scale Multiplier + References No definition available. + Details
Name: | pnm_PublicUtilitiesProfitIncentiveSlidingScaleMultiplier
Namespace Prefix: | pnm_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Program Costs Related To Energy Efficiency, in Year Four + References No definition available. + Details
Name: | pnm_PublicUtilitiesProgramCostsRelatedToEnergyEfficiencyInYearFour
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Program Costs Related To Energy Efficiency, in Year Three + References No definition available. + Details
Name: | pnm_PublicUtilitiesProgramCostsRelatedToEnergyEfficiencyInYearThree
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Program Costs Related To Energy Efficiency, in Year Two + References No definition available. + Details
Name: | pnm_PublicUtilitiesProgramCostsRelatedToEnergyEfficiencyInYearTwo
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Program Costs Related To Meter Installation + References No definition available. + Details
Name: | pnm_PublicUtilitiesProgramCostsRelatedToMeterInstallation
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Proposed Term to Provide Customers with Benefits Related to Reduction in State Corporate Income Tax Rate + References No definition available. + Details
Name: | pnm_PublicUtilitiesProposedTermtoProvideCustomerswithBenefitsRelatedtoReductioninStateCorporateIncomeTaxRate
Namespace Prefix: | pnm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Reasonable Cost Threshold In Megawatts Per Hour + References No definition available. + Details
Name: | pnm_PublicUtilitiesReasonableCostThresholdInMegawattsPerHour
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Regulatory Disallowance capital improvements + References No definition available. + Details
Name: | pnm_PublicUtilitiesRegulatoryDisallowancecapitalimprovements
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Renewable Energy Procurement Plan, Carrying Charges, Amount + References No definition available. + Details
Name: | pnm_PublicUtilitiesRenewableEnergyProcurementPlanCarryingChargesAmount
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Public Utilities, Renewable Energy Procurement Plan, Carrying Charges, Percent + References No definition available. + Details
Name: | pnm_PublicUtilitiesRenewableEnergyProcurementPlanCarryingChargesPercent
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Renewable Energy Procurement Plan, Proposed Recovery, Amount + References No definition available. + Details
Name: | pnm_PublicUtilitiesRenewableEnergyProcurementPlanProposedRecoveryAmount
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Public Utilities, Requested Rate increase (Decrease), non-fuel amount + References No definition available. + Details
Name: | pnm_PublicUtilitiesRequestedRateincreaseDecreasenonfuelamount
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Regulated Operations, Required Percentage of Renewable Energy in Portfolio to Electric Sales + References No definition available. + Details
Name: | pnm_PublicUtilitiesRequiredPercentageOfRenewableEnergyInPortfolioToElectricSales
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Return on Equity, Regulatory Disallowance + References No definition available. + Details
Name: | pnm_PublicUtilitiesReturnonEquityRegulatoryDisallowance
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Public Utilities, Revenue From Renewable Energy Rider, Year Two + References No definition available. + Details
Name: | pnm_PublicUtilitiesRevenueFromRenewableEnergyRiderYearTwo
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Public Utilities, Revenue from Renewable energy rider + References No definition available. + Details
Name: | pnm_PublicUtilitiesRevenuefromRenewableenergyrider
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Public Utilities, Solar generation capacity in Megawatts + References No definition available. + Details
Name: | pnm_PublicUtilitiesSolarGenerationCapacityInMegawatts
Namespace Prefix: | pnm_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, excess return on jurisdictional equity that would require refund + References No definition available. + Details
Name: | pnm_PublicUtilitiesexcessreturnonjurisdictionalequitythatwouldrequirerefund
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Regulatory Disallowance + References No definition available. + Details
Name: | pnm_RegulatoryDisallowance
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Utilities Operating Expense, Impairments, Portion Of Purchase Price + References No definition available. + Details
Name: | pnm_UtilitiesOperatingExpenseImpairmentsPortionOfPurchasePrice
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Discloses the amount of any reduction to the carrying amounts of regulated assets that result from impairment (for example, rate actions of a regulator). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6066304&loc=d3e44026-110379 + Details
Name: | us-gaap_AmountOfImpairmentToCarryingAmountOfRegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I.7) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32672-109319 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(9)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of public utility's requested return on equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of operating expense for impairments of regulated operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_UtilitiesOperatingExpenseImpairments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=pnm_PublicServiceCompanyOfNewMexicoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_A2015ElectricRateCaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_RenewablePortfolioStandardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_EnergyEfficiencyAndLoadManagementProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_IntegratedResourcePlan2011Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_IntegratedResourcePlan2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_IntegratedResourcePlan2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=pnm_NMPRCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_RenewableEnergyRiderMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_RenewableEnergyRiderSkyBlueEnergyProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_DateOfRegulatoryActionAxis=pnm_RequiredPercentageBy2011Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_DateOfRegulatoryActionAxis=pnm_RequiredPercentageBy2015Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_DateOfRegulatoryActionAxis=pnm_RequiredPercentageBy2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=pnm_PaloVerdeNuclearGeneratingStationUnit2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=pnm_NewMexicoWindMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_RenewablePortfolioStandard2014Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=pnm_RedMesaWindMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=pnm_LaJoyaWindMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pnm_FourCornersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnm_NewMexico2015RateCaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=pnm_PaloVerdeNuclearGeneratingStationUnits1And4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LeaseholdsAndLeaseholdImprovementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_TypeOfRegulatoryCostAxis=pnm_DisincentivesAndIncentivesAddedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_A2017EnergyEfficiencyAndLoadManagementProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_EnergyEfficiencyAndLoadManagementProgram2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |