XML 73 R56.htm IDEA: XBRL DOCUMENT
v3.20.2

Financing - Short-term Debt and Liquidity (Details) | 6 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2020 USD ($) | Dec. 31, 2017 USD ($) derivative | Jul. 24, 2020 USD ($) | Dec. 31, 2019 USD ($) | Jul. 22, 2019 USD ($) | Jul. 21, 2019 USD ($)
Short-term Debt [Line Items] |  |  |  |  |  |
Financing capacity |  |  |  |  | $ 50,000,000.0 | $ 40,000,000.0
Short-term debt | $ 252,549,000 |  |  | $ 185,100,000 |  |
Letters of credit outstanding | 4,600,000 |  |  |  |  |
Senior Unsecured Notes |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 300,000,000.0 |  |  |  |  |
Bonds |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 302,500,000 |  |  |  |  |
Pollution Control Revenue Bonds | Bonds |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 100,300,000 |  |  |  |  |
Long-term debt |  |  |  | 100,300,000 |  |
Variable Rate Short-Term Debt |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Term of derivatives |  | 4 years |  |  |  |
Aggregate principal amount |  | $ 50,000,000.0 |  |  |  |
PNMR Development Term Loan |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 90,000,000.0 |  |  |  |  |
PNMR 2018 Two Year Term Loan |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 50,000,000.0 |  |  |  |  |
Long-term debt | $ 50,000,000.0 |  |  |  |  |
Term of loan | 2 years |  |  |  |  |
PNMR Revolving Credit Facility | PNMR |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Line of credit facility, interest rate at period end | 1.68% |  |  |  |  |
PNM |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Short-term debt | $ 87,055,000 |  |  | 58,000,000 |  |
Letters of credit outstanding | 2,200,000 |  |  |  |  |
PNM | Lines of credit |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
NMPRC approved credit facility | 40,000,000.0 |  |  |  |  |
Short-term debt | 40,000,000 |  |  | 10,000,000 |  |
PNM | PNM 2019 Term Loan | Term loan agreement with banks |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 150,000,000.0 |  |  |  |  |
PNM | PNM 2019 40 Million Term Loan |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | 40,000,000.0 |  |  |  |  |
PNM | PNM 2020 250 Million Term Loan | Term loan agreement with banks |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | $ 150,000,000.0 |  |  |  |  |
PNM | PNM Revolving Credit Facility |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Line of credit facility, interest rate at period end | 1.43% |  |  |  |  |
PNM | PNM 2017 New Mexico Credit Facility |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Line of credit facility, interest rate at period end | 1.44% |  |  |  |  |
PNM | PNMR Development Revolving Credit Facility |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Letters of credit outstanding | $ 0 |  |  |  |  |
TNMP |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Short-term debt | 13,094,000 |  |  | 15,000,000 |  |
Letters of credit outstanding | 100,000 |  |  |  |  |
TNMP | PNMR Development Term Loan | Term loan agreement with banks |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Aggregate principal amount | $ 90,000,000.0 |  |  |  |  |
TNMP | TNMP Revolving Credit Facility |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Line of credit facility, interest rate at period end | 0.91% |  |  |  |  |
Revolving credit facility |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Financing capacity | $ 300,000,000.0 |  |  |  |  |
Short-term debt | 152,400,000 |  |  | 112,100,000 |  |
Revolving credit facility | PNM |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Financing capacity | 400,000,000.0 |  |  |  |  |
Short-term debt | 47,055,000 |  |  | 48,000,000 |  |
Revolving credit facility | TNMP |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Financing capacity | 75,000,000.0 |  |  |  |  |
Short-term debt | 12,600,000 |  |  | 15,000,000 |  |
Revolving credit facility | TNMP | First mortgage bonds |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Collateral amount | 75,000,000.0 |  |  |  |  |
Bonds | TNMP |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Short-term debt | 494,000 |  |  | 0 |  |
Interest rate contract |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Number of derivatives | derivative |  | 3 |  |  |  |
Interest rate 1 | Variable Rate Short-Term Debt |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Fixed interest rate |  | 1.926% |  |  |  |
Interest rate 2 | Variable Rate Short-Term Debt |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Fixed interest rate |  | 1.823% |  |  |  |
Interest rate 3 | Variable Rate Short-Term Debt |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Fixed interest rate |  | 1.629% |  |  |  |
Interest rate 3 | Level 2 | Cash Flow Hedge |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Current derivative liability | $ 2,100,000 |  |  | $ 400,000 |  |
Subsequent event |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  | $ 609,300,000 |  |  |
Subsequent event | PNMR |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  | 153,500,000 |  |  |
Consolidated invested cash |  |  | 900,000 |  |  |
Subsequent event | PNM |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  | 343,900,000 |  |  |
Consolidated invested cash |  |  | 0 |  |  |
Subsequent event | PNM | Lines of credit |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  | 0 |  |  |
Subsequent event | TNMP |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  | 74,900,000 |  |  |
Consolidated invested cash |  |  | 63,500,000 |  |  |
Subsequent event | PNMR Development |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  | $ 37,000,000.0 |  |  |

X
- Definition Debt Instruments, NMPRC Approved credit facility + References No definition available. + Details
Name: | pnm_DebtInstrumentsNMPRCApprovedcreditfacility
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of assets pledged to secure a debt instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentCollateralAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fixed interest rate related to the interest rate derivative. + References No definition available. + Details
Name: | us-gaap_DerivativeFixedInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
Name: | us-gaap_DerivativeLiabilitiesCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of derivative instruments of a particular group held by the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 + Details
Name: | us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The effective interest rate at the end of the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994 + Details
Name: | us-gaap_MaximumLengthOfTimeHedgedInInterestRateCashFlowHedge1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. + References No definition available. + Details
Name: | us-gaap_RestrictedCashAndInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(1)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
Name: | us-gaap_ShortTermBorrowings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ShortTermDebtLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=pnm_SeniorUnsecuredNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_NotesPayableOtherPayablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PollutionControlRevenueBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_VariableRateShortTermDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNMRDevelopmentTermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNMR2018TwoYearTermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=pnm_PNMRRevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_LocalLinesOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNM2019TermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_NotesPayableToBanksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNM201940MillionTermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNM2020250MillionTermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=pnm_PNMRevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=pnm_PNM2017NewMexicoCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=pnm_PNMRDevelopmentRevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_CreditFacilityAxis=pnm_TNMPRevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_FirstMortgageBondsDue2019Series2009Aat9point50percentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_NotesPayableOtherPayablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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