XML 113 R90.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Fair Value of Derivative and Other Financial Instruments - Narrative (Details) |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Apr. 17, 2023 MW | Jun. 30, 2022 MW | Dec. 31, 2023 USD ($) MW | Dec. 31, 2023 USD ($) MW | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) MW power_purchase_agreement | May 31, 2022 MW | Jan. 01, 2018 MW
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Contractual Liability |  |  | $ 0 | $ 0 | $ 15,288,000 |  |  |
Existing Cash Collateral |  |  | 0 | 0 | 0 |  |  |
Net Exposure |  |  | $ 0 | 0 | 13,087,000 |  |  |
Available for sale securities realized impairment losses |  |  |  | $ 19,100,000 | (25,800,000) | $ 700,000 |  |
Minimum |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets distribution period |  |  |  | 10 years |  |  |  |
Maximum |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets distribution period |  |  |  | 15 years |  |  |  |
Equity Securities | Pension Plan |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets |  |  | 35.00% | 35.00% |  |  |  |
Alternative Investments | Pension Plan |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets |  |  | 15.00% | 15.00% |  |  |  |
Fixed income | Pension Plan |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets |  |  | 50.00% | 50.00% |  |  |  |
PNM |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Number of purchase power agreements | power_purchase_agreement |  |  |  |  |  | 3 |  |
Number of purchase power agreement not considered derivatives | power_purchase_agreement |  |  |  |  |  | 2 |  |
Expected exposure to market risk (in megawatts) | MW |  |  | 65 | 65 |  |  |  | 65
Power to be sold to third party (in megawatts) | MW |  |  | 36 | 36 |  |  | 50 | 36
Amounts recognized for the legal right to reclaim cash collateral |  |  | $ 0 | $ 0 | 0 |  |  |
Amounts posted as cash collateral under margin arrangements |  |  | 200,000 | 200,000 | 10,500,000 |  |  |
Obligations to return cash collateral |  |  |  |  | 200,000 |  |  |
PNM | Commodity Contract | Designated as hedging instrument |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Derivative asset, fair value, gross liability |  |  | 0 | 0 |  |  |  |
Derivative asset, fair value, gross asset |  |  | 0 | 0 |  |  |  |
Other current assets |  |  | 826,000 | 826,000 | 9,780,000 |  |  |
Current derivative liability |  |  | 0 | 0 | 19,209,000 |  |  |
PNM | Fuel and purchased power costs | Commodity Contract | Designated as hedging instrument |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Other current assets |  |  | 800,000 | 800,000 | 9,800,000 |  |  |
Current derivative liability |  |  | $ 0 | $ 0 | 19,200,000 |  |  |
PNM | Portfolio One |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW | 420 | 85 |  |  |  | 85 |  |
PNM | Portfolio Two |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW |  |  | 40 | 375 |  | 40 |  |
PNM | Portfolio Three |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Number of megawatts available in purchase power agreement (in megawatts) | MW |  |  |  |  |  | 150 |  |
PNM | Tri-State |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Power to be sold to third party (in megawatts) | MW |  |  | 100 | 100 |  |  |  |
TNMP | Equity Securities | Pension Plan |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets |  |  | 16.00% | 16.00% |  |  |  |
TNMP | Alternative Investments | Pension Plan |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets |  |  | 14.00% | 14.00% |  |  |  |
TNMP | Fixed income | Pension Plan |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Investment allocation targets |  |  | 70.00% | 70.00% |  |  |  |
Measured on a recurring basis | PNM |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Debt securities, available-for-sale |  |  | $ 444,408,000 | $ 444,408,000 | 417,476,000 |  |  |
Nuclear Decommissioning Trust | Measured on a recurring basis | PNM |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Debt securities, available-for-sale |  |  | 361,000,000 | 361,000,000 | 325,300,000 |  |  |
Mine Reclamation Trust | Measured on a recurring basis | PNM |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Debt securities, available-for-sale |  |  | 71,100,000 | 71,100,000 | 77,500,000 |  |  |
SJGS Decommissioning Trust | Measured on a recurring basis | PNM |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Debt securities, available-for-sale |  |  | $ 12,300,000 | $ 12,300,000 | $ 14,700,000 |  |  |

X
- Definition Contract With Customer, Cash Collateral + References No definition available. + Details
Name: | pnm_ContractWithCustomerCashCollateral
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contract With Customer, Liability, Net + References No definition available. + Details
Name: | pnm_ContractWithCustomerLiabilityNet
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contract With Customer, Liability, Net Exposure + References No definition available. + Details
Name: | pnm_ContractWithCustomerLiabilityNetExposure
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Defined Benefit Plan, Periodic Distribution Period + References No definition available. + Details
Name: | pnm_DefinedBenefitPlanPeriodicDistributionPeriod
Namespace Prefix: | pnm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition (Increase)/Decrease In Other Than Temporary Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities + References No definition available. + Details
Name: | pnm_IncreaseDecreaseInOtherThanTemporaryLossesInvestmentsPortionRecognizedinEarningsNetAvailableforsaleSecurities
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number Of Purchase Power Agreement Not Considered Derivatives + References No definition available. + Details
Name: | pnm_NumberOfPurchasePowerAgreementNotConsideredDerivatives
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Purchase Power Agreements + References No definition available. + Details
Name: | pnm_NumberOfPurchasePowerAgreements
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Concentration Risk, Amount To Sell Due To Agreement + References No definition available. + Details
Name: | pnm_PublicUtilitiesConcentrationRiskAmountToSellDueToAgreement
Namespace Prefix: | pnm_
Data Type: | dtr-types1:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Concentration Risk, Potential Market Risk + References No definition available. + Details
Name: | pnm_PublicUtilitiesConcentrationRiskPotentialMarketRisk
Namespace Prefix: | pnm_
Data Type: | dtr-types1:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Number Of Megawatts Available In Purchase Power Agreement + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberOfMegawattsAvailableInPurchasePowerAgreement
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481830/320-10-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 8 -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-8 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 320 -Name Accounting Standards Codification -Section S99 -Paragraph 5C -Subparagraph (SX 210.12-13C(Column F)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5C Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 320 -Name Accounting Standards Codification -Section S99 -Paragraph 5B -Subparagraph (SX 210.12-13B(Column E)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5B Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B + Details
Name: | us-gaap_DerivativeAssetFairValueGrossLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 + Details
Name: | us-gaap_DerivativeAssetsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 13 -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-13 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 20 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-20 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-8 + Details
Name: | us-gaap_DerivativeCollateralObligationToReturnCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 13 -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-13 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 20 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-20 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-8 + Details
Name: | us-gaap_DerivativeCollateralRightToReclaimCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-22 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-7 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (c)(2) -SubTopic 20 -Topic 860 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481326/860-20-50-4D + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 + Details
Name: | us-gaap_DerivativeLiabilitiesCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of cash or securities placed with a broker or counterparty as security for a trading or derivatives securities position which was partially obtained with funds provided by the broker dealer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480524/946-210-50-6 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_MarginDepositAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aaa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=pnm_AlternativeInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

X
- Details
Name: | srt_CounterpartyNameAxis=pnm_TriStateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=pnm_NuclearDecommissioningTrustMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=pnm_MineReclamationTrustMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=pnm_SJGSDecommissioningTrustMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |