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Fair Value of Derivative and Other Financial Instruments, Defined Benefit Plans Disclosure (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | $ 2,173,117us-gaap_LongTermDebtFairValue / dei_LegalEntityAxis = pnm_PnmrMember | $ 1,905,230us-gaap_LongTermDebtFairValue / dei_LegalEntityAxis = pnm_PnmrMember |
Investment in PVNGS lessor notes | 32,836pnm_InvestmentInLessorNotesFairValueDisclosure / dei_LegalEntityAxis = pnm_PnmrMember | 57,279pnm_InvestmentInLessorNotesFairValueDisclosure / dei_LegalEntityAxis = pnm_PnmrMember |
Other investments | 2,375pnm_OtherInvestmentsFairValueDisclosure / dei_LegalEntityAxis = pnm_PnmrMember | 3,196pnm_OtherInvestmentsFairValueDisclosure / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 657,319us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / dei_LegalEntityAxis = pnm_PnmrMember | 623,543us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / dei_LegalEntityAxis = pnm_PnmrMember |
Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 1,624,222us-gaap_LongTermDebtFairValue / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 1,382,938us-gaap_LongTermDebtFairValue / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Investment in PVNGS lessor notes | 32,836pnm_InvestmentInLessorNotesFairValueDisclosure / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 57,279pnm_InvestmentInLessorNotesFairValueDisclosure / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other investments | 397pnm_OtherInvestmentsFairValueDisclosure / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 445pnm_OtherInvestmentsFairValueDisclosure / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 427,356us-gaap_LongTermDebtFairValue / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 390,814us-gaap_LongTermDebtFairValue / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other investments | 242pnm_OtherInvestmentsFairValueDisclosure / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 245pnm_OtherInvestmentsFairValueDisclosure / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Cash and Cash Equivalents [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 15,645us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / dei_LegalEntityAxis = pnm_PnmrMember | 16,281us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Equity Securities, International Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 23,282us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / dei_LegalEntityAxis = pnm_PnmrMember | 24,471us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Equity Securities, Domestic Value [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 41,778us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / dei_LegalEntityAxis = pnm_PnmrMember | 41,451us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / dei_LegalEntityAxis = pnm_PnmrMember |
Equity Securities, Domestic Growth [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 28,370us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / dei_LegalEntityAxis = pnm_PnmrMember | 36,805us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / dei_LegalEntityAxis = pnm_PnmrMember |
Equity Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 29,719us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / dei_LegalEntityAxis = pnm_PnmrMember | 22,522us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Fixed Income Securities, Corporate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 242,742us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / dei_LegalEntityAxis = pnm_PnmrMember | 202,897us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / dei_LegalEntityAxis = pnm_PnmrMember |
Fixed Income Securities, U.S. Government [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 106,634us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / dei_LegalEntityAxis = pnm_PnmrMember | 99,748us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / dei_LegalEntityAxis = pnm_PnmrMember |
Fixed Income Securities, Municipals [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 20,156us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / dei_LegalEntityAxis = pnm_PnmrMember | 17,259us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Fixed Income Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 74,136us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / dei_LegalEntityAxis = pnm_PnmrMember | 66,286us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Private Equity Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 37,220us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / dei_LegalEntityAxis = pnm_PnmrMember | 39,122us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Hedge Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 23,876us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / dei_LegalEntityAxis = pnm_PnmrMember | 34,912us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / dei_LegalEntityAxis = pnm_PnmrMember |
Real Estate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 13,761us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / dei_LegalEntityAxis = pnm_PnmrMember | 21,789us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Investment in PVNGS lessor notes | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Other investments | 639pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 690pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 138,491us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 164,021us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Investment in PVNGS lessor notes | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other investments | 397pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 445pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other investments | 242pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 245pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 15,645us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 16,281us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Equity Securities, International Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 24,471us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Equity Securities, Domestic Value [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 41,778us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 41,451us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Equity Securities, Domestic Growth [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 28,370us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 36,805us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Fixed Income Securities, Corporate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 363us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Fixed Income Securities, U.S. Government [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 52,537us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 44,541us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Fixed Income Securities, Municipals [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Fixed Income Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 161us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 109us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Private Equity Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Hedge Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 1 [Member] | Real Estate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 2,173,117us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 1,905,230us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Investment in PVNGS lessor notes | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Other investments | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 443,244us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 363,523us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 1,624,222us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 1,382,938us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Investment in PVNGS lessor notes | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other investments | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 427,356us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 390,814us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other investments | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Equity Securities, International Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 23,282us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Equity Securities, Domestic Value [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Equity Securities, Domestic Growth [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Equity Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 29,719us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 22,522us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Fixed Income Securities, Corporate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 242,015us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 202,358us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Fixed Income Securities, U.S. Government [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 54,097us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 55,207us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Fixed Income Securities, Municipals [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 20,156us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 17,259us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Fixed Income Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 73,975us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 66,177us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Private Equity Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Hedge Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 2 [Member] | Real Estate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Investment in PVNGS lessor notes | 32,836pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 57,279pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Other investments | 1,736pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 2,506pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 75,584us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 95,999us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Investment in PVNGS lessor notes | 32,836pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 57,279pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other investments | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_LongTermDebtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other investments | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair Value, Inputs, Level 3 [Member] | PNMR Master Trust [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 75,584us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 95,999us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
Fair Value, Inputs, Level 3 [Member] | PNMR Master Trust [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 80,991us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 79,017us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Actual return on assets sold during the period | 10,376us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 3,303us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Actual return on assets still held at period end | (5,731)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 3,361us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 8,832us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 15,110us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (28,843)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (19,800)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair value of plan assets at end of year | 65,625us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 80,991us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair Value, Inputs, Level 3 [Member] | PNMR Master Trust [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 15,008us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 14,171us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Actual return on assets sold during the period | 3,409us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,400us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Actual return on assets still held at period end | (1,883)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,425us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 2,902us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 6,408us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (9,477)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (8,396)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair value of plan assets at end of year | 9,959us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 15,008us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Equity Securities, International Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Equity Securities, Domestic Value [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Equity Securities, Domestic Growth [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Equity Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Fixed Income Securities, Corporate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 176us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets sold during the period | 0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets still held at period end | (20)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 608us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 175us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (37)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 727us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 176us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesCorporateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Fixed Income Securities, U.S. Government [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesUSGovernmentMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Fixed Income Securities, Municipals [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesMunicipalsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Fixed Income Securities, Other Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_FixedIncomeSecuritiesOtherFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 39,122us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 38,212us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets sold during the period | 5,355us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 4,677us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets still held at period end | (296)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 1,162us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 3,656us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 3,117us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (10,617)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | (8,046)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 37,220us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 39,122us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 34,912us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 31,277us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets sold during the period | 8,667us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 135us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets still held at period end | (7,536)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 3,500us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 5,500us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 16,151us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (17,667)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | (16,151)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 23,876us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 34,912us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 21,789us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 23,699us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets sold during the period | (236)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | (109)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets still held at period end | 237us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 123us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 1,971us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 2,076us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (10,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | (4,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 13,761us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 21,789us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Inputs, Level 3 [Member] | Private Equity, Hedge and Real Estate Funds [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year | 95,999us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 93,188us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets sold during the period | 13,786us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 4,704us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Actual return on assets still held at period end | (7,615)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 4,785us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 11,735us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 21,519us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (38,321)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | (28,197)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Fair value of plan assets at end of year | 75,584us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember | 95,999us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_PrivateEquityHedgeAndRealEstateFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PnmrMember |
Pension Plan [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year |  |  | 518,095us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Fair value of plan assets at end of year | 587,909us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 556,353us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 518,095us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Pension Plan [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at beginning of year |  |  | 66,540us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Fair value of plan assets at end of year | 69,177us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 66,118us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 66,540us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Pension Plan [Member] | PNMR Master Trust [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 588,112us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 557,258us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Pension Plan [Member] | PNMR Master Trust [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 69,207us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 66,285us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member] | PNMR Master Trust [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 123,668us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 145,364us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member] | PNMR Master Trust [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 14,823us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 18,657us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member] | PNMR Master Trust [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 398,819us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 330,903us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member] | PNMR Master Trust [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 44,425us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 32,620us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Pension Plan [Member] | Fair Value, Inputs, Level 3 [Member] | PNMR Master Trust [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 65,625us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 80,991us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Pension Plan [Member] | Fair Value, Inputs, Level 3 [Member] | PNMR Master Trust [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 9,959us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 15,008us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_TrustForBenefitOfEmployeesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period | 79,018pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 74,133pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Fair value of plan assets at beginning of year |  |  | 64,464us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Fair value of plan assets at end of year | 78,175us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 73,565us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 64,464us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Other Postretirement Benefits [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period | 10,211pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 9,734pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Fair value of plan assets at beginning of year |  |  | 8,643us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Fair value of plan assets at end of year | 10,094us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 9,601us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 8,643us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 1,242us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 1,152us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 168us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 302us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 10,332us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 11,634us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 1,277us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,334us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 8,365us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 6,388us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 403us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 381us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 5,960us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 24,135us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 1,024us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 4,171us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Equity Securities, Other Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 30,997us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 14,028us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Equity Securities, Other Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 3,790us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,844us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fixed income securities, Mutual funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 22,122us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 16,796us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fixed income securities, Mutual funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 3,549us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,702us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period | 37,689pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 31,430pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period | 5,144pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 4,233pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 1,242us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 1,152us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 168us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 302us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, International Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, International Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Domestic Value [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 8,365us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 6,388us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Domestic Value [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 403us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 381us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Domestic Growth [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 5,960us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 7,094us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Domestic Growth [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 1,024us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,848us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed income securities, Mutual funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 22,122us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 16,796us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed income securities, Mutual funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 3,549us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,702us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period | 41,329pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 42,703pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period | 5,067pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 5,501pnm_DefinedBenefitPlanFairValueOfPlanTotalAssetsOwnedAtEndOfPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, International Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 10,332us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 11,634us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, International Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 1,277us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 1,334us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesInternationalFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, Domestic Value [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, Domestic Value [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, Domestic Growth [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, Domestic Growth [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, Other Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities, Other Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed income securities, Mutual funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed income securities, Mutual funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, International Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, International Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, Domestic Value [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, Domestic Value [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, Domestic Growth [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, Domestic Growth [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesDomesticGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, Other Funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pnm_EquitySecuritiesOtherFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities, Other Funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
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Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed income securities, Mutual funds [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed income securities, Mutual funds [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets at end of year | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_FixedIncomeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Carrying (Reported) Amount, Fair Value Disclosure [Member] | PNMR [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 1,975,090us-gaap_LongTermDebtFairValue / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PnmrMember | 1,745,420us-gaap_LongTermDebtFairValue / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PnmrMember |
Investment in PVNGS lessor notes | 31,232pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PnmrMember | 52,958pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PnmrMember |
Other investments | 1,762pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PnmrMember | 1,835pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PnmrMember |
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Public Service Company of New Mexico [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 1,490,657us-gaap_LongTermDebtFairValue / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 1,290,618us-gaap_LongTermDebtFairValue / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Investment in PVNGS lessor notes | 31,232pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 52,958pnm_InvestmentInLessorNotesFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Other investments | 397pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 445pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember |
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Texas-New Mexico Power Company [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Long-term debt | 365,667us-gaap_LongTermDebtFairValue / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 336,036us-gaap_LongTermDebtFairValue / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |
Other investments | $ 242pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | $ 245pnm_OtherInvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember |

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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930 + Details
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