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Regulatory and Rate Matters - PNM (Details) $ in Millions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jul. 26, 2017 USD ($) GWh | Jul. 03, 2017 | Jun. 01, 2017 USD ($) GWh MW | May 23, 2017 USD ($) | Apr. 14, 2017 USD ($) GWh program | Mar. 27, 2017 | Feb. 28, 2017 USD ($) | Jan. 11, 2017 USD ($) | Dec. 07, 2016 USD ($) | Sep. 28, 2016 USD ($) MW | Aug. 04, 2016 USD ($) MW | Jun. 01, 2016 MW | May 04, 2016 | Apr. 15, 2016 USD ($) GWh program | Jan. 15, 2016 USD ($) lease MW | Nov. 30, 2015 | Aug. 27, 2015 USD ($) | Jan. 15, 2015 | Jul. 01, 2014 | Sep. 30, 2016 USD ($) | Dec. 31, 2015 USD ($) MW | Jun. 30, 2017 USD ($) GWh lease meeting MW | Jun. 30, 2016 USD ($) | Jun. 30, 2017 USD ($) GWh lease meeting MW | Jun. 30, 2016 USD ($) | Dec. 31, 2016 USD ($) GWh | Dec. 31, 2015 MW | May 05, 2017 signatory | Oct. 26, 2016 MW | Jul. 08, 2016 service_rate MW | Apr. 26, 2016 MW | Feb. 26, 2016 USD ($) | Jan. 31, 2016 lease MW
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Excess return on jurisdictional equity that would require refund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  | 0.50% |  |  |  |  |  |  |  |  |
Application filed for new electric service rates | service_rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |
NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  |  |  |  | $ 99.2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested return on equity |  |  |  |  |  |  |  |  | 10.125% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unopposed motion filed for extension of procedural schedule |  |  |  |  |  | 1 month |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of additional signatories | signatory |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 13 |  |  |  |  |
Period of time for proposed return to customers the benefit of the reduction in New Mexico's corporate income tax rate |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Return on equity, regulatory disallowance |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 21.0 |  | $ 21.0 |  |  |  |  |  |  |  |  |
Proposed revision to rider that will allow for recovery |  |  | $ 43.5 |  |  |  | $ 42.7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Action plan, covered period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years |  |  |  |  |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of statewide meetings hosted | meeting |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 17 |  | 17 |  |  |  |  |  |  |  |  |
PNM | Tri-State |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of hazard sharing agreement |  |  |  |  |  |  |  |  |  |  |  | 1 year |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Each party will sell the other party capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  | 100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of hours sold (in gigawatt hours) | GWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 199.0 |  | 412.6 |  | 482.3 |  |  |  |  |  |  |
Hours sold, amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5.7 |  | $ 10.5 |  | $ 12.8 |  |  |  |  |  |  |
Number of hours purchased (in gigawatt hours) | GWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 212.2 |  | 417.4 |  | 484.6 |  |  |  |  |  |  |
Hours purchased, amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6.1 |  | $ 10.6 |  | $ 12.9 |  |  |  |  |  |  |
PNM | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Planning period covered of IRP |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Action plan, covered period |  | 4 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  | $ 62.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested return on equity |  |  |  | 9.575% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested initial rate increase (decrease) |  |  |  | $ 32.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time for proposed return to customers the benefit of the reduction in New Mexico's corporate income tax rate |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested approval to procure additional gigawatt hours in year 1 | GWh |  |  | 80 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested approval to procure a new solar facilities to be constructed (in megawatts) | MW |  |  | 50 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Action plan, covered period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notice of Proposed Dismissal, period to show good cause |  |  |  |  |  |  |  |  |  |  |  |  | 30 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | NMPRC | Tri-State |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of hazard sharing agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |
PNM | NMPRC | New Mexico Wind |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested approval to procure additional gigawatt hours in year 2 | GWh |  |  | 105 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | NMPRC | Lightning Dock Geothermal |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested approval to procure additional gigawatt hours in year 1 | GWh |  |  | 55 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested approval to procure additional gigawatt hours in year 2 | GWh |  |  | 77 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Units 1 and 4 | Clean Air Act, Balanced Draft Technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net book value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.0 |  | $ 50.0 |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Units 1 and 4 | Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other Costs | Clean Air Act, Balanced Draft Technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Installation costs |  |  |  |  |  |  |  |  |  |  | $ 52.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Units 1 and 4 | Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other Costs | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Installation costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 77.9 |  |  |  |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Units 2 and 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net book value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 262.8 |  | $ 262.8 |  |  |  |  |  |  |  |  |
PNM | San Juan Generating Station Units 2 and 3 | Clean Air Act, SNCR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Newly identified replacement gas-fired generation (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 80 |  |
Replacement gas-fired aeroderivative generation (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40 |  | 40 |  |  |  |  |  |  |  |  |
PNM | Palo Verde Nuclear Generating Station, Unit 2 Leases |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts purchased (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 64.1 |  |  |  |  |  |  | 64.1 |  | 64.1 |  |  |  |  |  |  |  |  | 64.1
Number of leases under which assets were purchased | lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  | 3 |  | 3 |  |  |  |  |  |  |  |  | 3
Estimated annual property tax expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.8 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of leases under which lease term was extended | lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease term extension period |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts nuclear generation (in megawatts) | MW |  |  |  |  |  |  |  |  |  | 114.6 | 114.6 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 114.6 |  |  |  |
Net book value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 76.9 |  | $ 76.9 |  |  |  |  |  |  |  |  |
Net book value of capitalized improvements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 39.9 |  | 39.9 |  |  |  |  |  |  |  |  |
PNM | Palo Verde Nuclear Generating Station, Unit 1 Leases, extended |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated annual property tax expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated annual rent expense |  |  |  |  |  |  |  |  |  |  | $ 18.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of leases under which lease term was extended | lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease term extension period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | 2015 Electric Rate Case |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 123.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) of non-fuel revenue |  |  |  |  |  |  |  |  |  |  | 121.5 |  |  |  |  |  | $ 121.7 |  |  |  |  |  |  | 121.5 |  |  |  |  |  |  |  |  |
Requested return on equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) for fuel related costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (42.9) |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) for non-fuel related revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (0.2) |  |  |  |  |  |  |  |  |
Hearing examiner's recommended rate increase (decrease) of non-fuel revenue |  |  |  |  |  |  |  |  |  |  | $ 41.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hearing examiner's recommended return on equity |  |  |  |  |  |  |  |  |  |  | 9.575% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Approved rate increase (decrease) |  |  |  |  |  |  |  |  |  | $ 61.2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated period of time for supreme court appeal decision |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 months |  |  |  |  |  |  |  |  |  |  |  |  |
Approved recovery of net operating loss carryforward |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2.1 |  |  |  |  |  |  |  |  |  |  |  |  |
Estimate of possible loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 154.2 |  | $ 154.2 |  |  |  |  |  |  |  |  |
PNM | 2015 Electric Rate Case | San Juan Generating Station Units 1 and 4 | Clean Air Act, Balanced Draft Technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested base rate increase (decrease) |  |  |  |  |  |  |  |  |  |  | $ 40.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | 2015 Electric Rate Case | San Juan Generating Station | Refined coal |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hearing examiner's recommended percentage of revenue to be credited to customers |  |  |  |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | 2015 Electric Rate Case | Palo Verde Nuclear Generating Station, Unit 2 Leases |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hearing examiner's proposed disallowance of recovery |  |  |  |  |  |  |  |  |  |  | $ 163.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial rate base value |  |  |  |  |  |  |  |  |  | 83.7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disallowance of the recovery underpreciated costs of capitalized leasehold improvements |  |  |  |  |  |  |  |  |  | 43.8 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time for which capital improvements were disallowed |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 months |  |  |  |  |  |  |  |  |  |  |  |  |
Pre-tax regulatory disallowance |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6.8 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | 2015 Electric Rate Case | Palo Verde Nuclear Generating Station, Unit 1 Leases, extended |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recovery of assumed operating and maintenance expense savings annually |  |  |  |  |  |  |  |  |  | $ 0.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | 2015 Electric Rate Case | Alvarado square |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hearing examiner's recommended amount to not be recovered from retail customers |  |  |  |  |  |  |  |  |  |  | $ 4.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pre-tax regulatory disallowance of costs recorded as regulatory assets and deferred charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4.5 |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | 2014 Electric Rate Case |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of time after the filing of a rate case application |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 13 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts of Solar PV facilities | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40 | 107 |  | 107 |  |  | 40 |  |  |  |  |  |
Current output in the geothermal facility (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  | 4 |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 72.0 |  | 72.0 |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Profit incentive sliding scale multiplier |  |  |  |  |  |  |  | 7.10% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reasonable cost threshold |  |  |  |  |  |  |  | 3.00% |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.00% |  | 3.00% |  |  |  |  |  |  |  |  |
Profit incentive sliding scale multiplier |  |  |  |  |  |  |  | 9.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Wind | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of diversification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 30.00% |  | 30.00% |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Solar | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of diversification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20.00% |  | 20.00% |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Distributed generation | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of diversification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.00% |  | 3.00% |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Other | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of diversification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.00% |  | 5.00% |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Required Percentage by 2011 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  | 10.00% |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Required Percentage by 2015 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15.00% |  | 15.00% |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard | Required Percentage by 2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required percentage of renewable energy in portfolio to electric sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20.00% |  | 20.00% |  |  |  |  |  |  |  |  |
PNM | Proposed 2018 Portfolio | Disincentives/Incentives Adder |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of programs in the proposed program portfolio | program |  |  |  |  | 10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program portfolio's total budget |  |  |  |  | $ 25.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Incentive based on target savings |  |  |  |  | $ 1.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Targeted savings (in gigawatt hours) | GWh |  |  |  |  | 53 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Projected incentive earnings |  |  |  |  | $ 2.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Targeted savings (in gigawatt hours) | GWh |  |  |  |  | 70 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Proposed 2018 Portfolio | Disincentives/Incentives Adder | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Projected incentive earnings | $ 1.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Targeted savings (in gigawatt hours) | GWh | 69 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Proposed 2019 Portfolio | Disincentives/Incentives Adder |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of programs in the proposed program portfolio | program |  |  |  |  | 10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program portfolio's total budget |  |  |  |  | $ 28.2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Incentive based on target savings |  |  |  |  | $ 2.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Proposed 2019 Portfolio | Disincentives/Incentives Adder | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Incentive based on target savings | $ 1.7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard Supplemental Procurement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts of Solar PV facilities | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.5 |  | 1.5 |  |  |  |  |  |  |  |  |
PNM | Renewable Portfolio Standard 2014 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts for wind energy | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 204 |  |  | 102 |  |  |  |  |  |
PNM | Renewable Energy Rider |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recorded revenues from renewable rider |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 9.6 | $ 8.2 | $ 20.5 | $ 16.6 |  |  |  |  |  |  |  |
PNM | Renewable Energy Rider | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposal to collect funds under renewable energy procurement plan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 42.4 |  |  |  |  |  |  |
Annual revenue to be collected under rider rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.0 |  | $ 50.0 |  |  |  |  |  |  |  |  |
PNM | 2017 Energy Efficiency and Load Management Program | Disincentives/Incentives Adder |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of programs in the proposed program portfolio | program |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program portfolio's total budget |  |  |  |  |  |  |  | $ 26.0 |  |  |  |  |  | $ 28.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Incentive based on target savings |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2.4 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Targeted savings (in gigawatt hours) | GWh |  |  |  |  |  |  |  |  |  |  |  |  |  | 75 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Profit incentive |  |  |  |  |  |  |  | $ 1.8 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PNM | Integrated Resource Plan, 2011 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Frequency of IRP filings |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |
Planning period covered of IRP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20 years |  |  |  |  |  |  |  |  |
PNM | Advanced Metering Infrastructure Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated costs to be recovered |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 87.2 |
Estimated future investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 33.0 |
PNM | Firm Requirements Wholesale Power Rate Case, Navopache |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of megawatts served under a short-term coordination tariff | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 |  |  |  |  |  |  |  |  |
Revenue for power sold under PSA |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.1 | $ 4.7 | $ 2.2 | $ 10.0 |  |  |  |  |  |  |  |
PNMR Development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 30 |  |  |
Construction of solar generation capacity (in megawatts) | MW |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 |  |  |

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