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Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | $ (58,140)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | $ (81,630)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | $ (66,856)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Amounts reclassified from AOCI (pre-tax) | (8,152)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax | (5,385)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax | (32,476)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax
Income tax impact of amounts reclassified | 3,234pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome | 2,137pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome | 12,865pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome
Other OCI changes (pre-tax) | 2,038us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax | 44,276us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax | 8,036us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax
Income tax impact of other OCI changes | (735)us-gaap_OtherComprehensiveIncomeLossTax | (17,538)us-gaap_OtherComprehensiveIncomeLossTax | (3,199)us-gaap_OtherComprehensiveIncomeLossTax
Total Other Comprehensive Income (Loss) | (3,615)us-gaap_OtherComprehensiveIncomeLossNetOfTax | 23,490us-gaap_OtherComprehensiveIncomeLossNetOfTax | (14,774)us-gaap_OtherComprehensiveIncomeLossNetOfTax
Ending Balance | (61,755)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | (58,140)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | (81,630)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Percentage of Pension Liability Adjustment Capitalized into Construction Work In Process | 24.40%pnm_PercentageofPensionLiabilityAdjustmentCapitalizedintoConstructionWorkInProcess | 18.70%pnm_PercentageofPensionLiabilityAdjustmentCapitalizedintoConstructionWorkInProcess |
Percentage of Pension Liability Adjustment Capitalized into Other Accounts | 2.00%pnm_PercentageOfPensionLiabilityAdjustmentCapitalizedIntoOtherAccounts | 3.00%pnm_PercentageOfPensionLiabilityAdjustmentCapitalizedIntoOtherAccounts |
Public Service Company of New Mexico [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | (57,877)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (81,414)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (66,798)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Amounts reclassified from AOCI (pre-tax) | (8,710)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (5,592)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (32,658)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Income tax impact of amounts reclassified | 3,429pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 2,210pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 12,930pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Other OCI changes (pre-tax) | 2,191us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 44,555us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 8,464us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Income tax impact of other OCI changes | (788)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (17,636)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (3,352)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Total Other Comprehensive Income (Loss) | (3,878)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | 23,537us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (14,616)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Ending Balance | (61,755)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (57,877)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember | (81,414)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember
Texas-New Mexico Power Company [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | (263)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (216)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (58)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Amounts reclassified from AOCI (pre-tax) | 558us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 207us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 182us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Income tax impact of amounts reclassified | (195)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (73)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (65)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Other OCI changes (pre-tax) | (153)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (279)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (428)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Income tax impact of other OCI changes | 53us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 98us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | 153us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Total Other Comprehensive Income (Loss) | 263us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (47)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (158)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Ending Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (263)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember | (216)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember
Accumulated Net Unrealized Investment Gain (Loss) [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | 25,748us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 16,406us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 15,634us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Amounts reclassified from AOCI (pre-tax) | (13,862)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (11,956)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (37,269)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Income tax impact of amounts reclassified | 5,461pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 4,734pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 14,755pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Other OCI changes (pre-tax) | 17,473us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 27,419us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 38,548us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Income tax impact of other OCI changes | (6,812)us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (10,855)us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (15,262)us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Total Other Comprehensive Income (Loss) | 2,260us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 9,342us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 772us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Ending Balance | 28,008us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 25,748us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 16,406us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Public Service Company of New Mexico [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | 25,748us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 16,406us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 15,634us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Amounts reclassified from AOCI (pre-tax) | (13,862)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (11,956)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (37,269)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Income tax impact of amounts reclassified | 5,461pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 4,734pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 14,755pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Other OCI changes (pre-tax) | 17,473us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 27,419us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 38,548us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Income tax impact of other OCI changes | (6,812)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (10,855)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | (15,262)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Total Other Comprehensive Income (Loss) | 2,260us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 9,342us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 772us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Ending Balance | 28,008us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 25,748us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 16,406us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Texas-New Mexico Power Company [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Amounts reclassified from AOCI (pre-tax) | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Income tax impact of amounts reclassified | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Other OCI changes (pre-tax) | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Income tax impact of other OCI changes | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Total Other Comprehensive Income (Loss) | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Ending Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Accumulated Defined Benefit Plans Adjustment [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | (83,625)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (97,820)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (82,432)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Amounts reclassified from AOCI (pre-tax) | 5,152us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 6,364us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 4,611us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Income tax impact of amounts reclassified | (2,032)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (2,524)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (1,825)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Other OCI changes (pre-tax) | (15,282)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 17,136us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (30,084)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Income tax impact of other OCI changes | 6,024us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (6,781)us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 11,910us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Total Other Comprehensive Income (Loss) | (6,138)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 14,195us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (15,388)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Ending Balance | (89,763)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (83,625)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (97,820)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Accumulated Defined Benefit Plans Adjustment [Member] | Public Service Company of New Mexico [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | (83,625)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (97,820)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (82,432)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Amounts reclassified from AOCI (pre-tax) | 5,152us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 6,364us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 4,611us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Income tax impact of amounts reclassified | (2,032)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (2,524)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (1,825)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Other OCI changes (pre-tax) | (15,282)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 17,136us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (30,084)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Income tax impact of other OCI changes | 6,024us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (6,781)us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 11,910us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Total Other Comprehensive Income (Loss) | (6,138)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 14,195us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (15,388)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Ending Balance | (89,763)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (83,625)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (97,820)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Accumulated Defined Benefit Plans Adjustment [Member] | Texas-New Mexico Power Company [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Amounts reclassified from AOCI (pre-tax) | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Income tax impact of amounts reclassified | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Other OCI changes (pre-tax) | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Income tax impact of other OCI changes | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Total Other Comprehensive Income (Loss) | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Ending Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | (263)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (216)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (58)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Amounts reclassified from AOCI (pre-tax) | 558us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 207us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 182us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Income tax impact of amounts reclassified | (195)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (73)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (65)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Other OCI changes (pre-tax) | (153)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (279)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (428)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Income tax impact of other OCI changes | 53us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 98us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 153us-gaap_OtherComprehensiveIncomeLossTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Total Other Comprehensive Income (Loss) | 263us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (47)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (158)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Ending Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (263)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (216)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Public Service Company of New Mexico [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Amounts reclassified from AOCI (pre-tax) | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Income tax impact of amounts reclassified | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Other OCI changes (pre-tax) | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Income tax impact of other OCI changes | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Total Other Comprehensive Income (Loss) | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Ending Balance | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_PublicServiceCompanyOfNewMexicoMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Texas-New Mexico Power Company [Member] |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Beginning Balance | (263)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (216)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (58)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Amounts reclassified from AOCI (pre-tax) | 558us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 207us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 182us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Income tax impact of amounts reclassified | (195)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (73)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (65)pnm_IncomeTaxImpactOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncome / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Other OCI changes (pre-tax) | (153)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (279)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (428)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Income tax impact of other OCI changes | 53us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 98us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 153us-gaap_OtherComprehensiveIncomeLossTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Total Other Comprehensive Income (Loss) | 263us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (47)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (158)us-gaap_OtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Ending Balance | $ 0us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | $ (263)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | $ (216)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / dei_LegalEntityAxis = pnm_TexasNewMexicoPowerCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember

X
- Details
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Namespace Prefix: | pnm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Income tax impact of amounts reclassified from accumulated other comprehensive income + References No definition available. + Details
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Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of Pension Liability Adjustment Capitalized into Construction Work In Process + References No definition available. + Details
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Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage of Pension Liability Adjustment Capitalized into Other Accounts + References No definition available. + Details
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Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
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