XML 69 R54.htm IDEA: XBRL DOCUMENT
v3.20.1

Financing - Financing Activities (Details) |  |  |  |  |  |  |  | 3 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 30, 2020 USD ($) | Apr. 24, 2020 USD ($) bond_series | Apr. 15, 2020 USD ($) | Apr. 01, 2020 USD ($) | Jan. 08, 2020 $ / shares shares | Jan. 07, 2020 shares | Jul. 01, 2019 USD ($) | Mar. 31, 2020 USD ($) shares | Mar. 31, 2019 | Jul. 15, 2020 USD ($) | May 01, 2020 | Dec. 31, 2019 shares | Oct. 21, 2016 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued (in shares) | shares |  |  |  |  |  |  |  | 79,653,624 |  |  |  | 79,653,624 |
PNMR 2020 Forward Equity Sales Agreement |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued (in shares) | shares |  |  |  |  |  | 6,200,000 |  |  |  |  |  |  |
Sale of stock, price per share (in dollars per share) | $ / shares |  |  |  |  | $ 47.21 |  |  |  |  |  |  |  |
Over-Allotment Option |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction (in shares) | shares |  |  |  |  | 800,000 | 800,000 |  |  |  |  |  |  |
PNMR 2016 Two-Year Term Loan |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 1.79% |  |  |  |  |
Term loans |  |  |  |  |  |  |  | $ 50,000,000.0 |  |  |  |  |
Term of loan |  |  |  |  |  |  |  | 2 years |  |  |  |  |
PNMR 2019 Term Loan |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 1.75% |  |  |  |  |
PNMR Development Term Loan |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  | $ 90,000,000.0 |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued (in shares) | shares |  |  |  |  |  |  |  | 39,117,799 |  |  |  | 39,117,799 |
Term loans |  |  |  |  |  |  |  | $ 100,300,000 |  |  |  |  |
PNM | PNM 2019 40 Million Term Loan |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  | $ 40,000,000.0 |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 1.26% |  |  |  |  |
PNM | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Maturity term over which financings require regulator approval (more than) |  |  |  |  |  |  |  | 18 months |  |  |  |  |
Texas-New Mexico Power Company |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued (in shares) | shares |  |  |  |  |  |  |  | 6,358 |  |  |  | 6,358 |
Line of credit |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Ratio of debt to capital (less than or equal to) |  |  |  |  |  |  |  | 65.00% | 70.00% |  |  |  |
Line of credit | PNM | PNM Revolving Credit Facility | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt | $ 100,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Letter of credit | PNMR | JPM LOC Facility |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  |  |  |  | $ 30,300,000
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 185,000,000.0 |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Ratio of debt to capital (less than or equal to) |  | 65.00% |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  | $ 110,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Series of bond issuance | bond_series |  | 4 |  |  |  |  |  |  |  |  |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement, Bond Series 1 | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  | $ 85,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  | 2.73% |  |  |  |  |  |  |  |  |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement, Bond Series 2 | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  | $ 25,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  | 3.36% |  |  |  |  |  |  |  |  |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement, Bond Series 3 | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 25,000,000.0 |  |  |
Stated interest rate |  |  |  |  |  |  |  |  |  | 2.93% |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement, Bond Series 4 | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 50,000,000.0 |  |  |
Stated interest rate |  |  |  |  |  |  |  |  |  | 3.36% |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement, Bond Series 1 and 2 | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  | $ 110,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2020 Bond Purchase Agreement, Bond Series 3 and 4 | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 75,000,000.0 |  |  |
Medium-term Notes | PNM | PNM 2020 250 Million Term Loan | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt |  |  | $ 250,000,000.0 |  |  |  |  |  |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  |  |  |  | 2.70% |  |
Senior Unsecured Notes |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  | $ 300,000,000.0 |  |  |  |  |
Senior Notes | Senior Unsecured Notes, 3.21% Series A, due April 2030 | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount | $ 150,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate | 3.21% |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes | Senior Unsecured Notes, 3.57% Series B, due April 2039 | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount | $ 50,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate | 3.57% |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes | PNM | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Ratio of debt to capital (less than or equal to) | 65.00% |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount | $ 200,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes | PNM | PNM 2020 250 Million Term Loan | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt | $ 100,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Term loan agreement with banks | PNM | PNM 2019 Term Loan | JPMorgan Chase Bank, N.A. and U.S. Bank National Association |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  | $ 250,000,000.0 |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 1.59% |  |  |  |  |
Term loan agreement with banks | Texas-New Mexico Power Company | PNMR Development Term Loan | JPMorgan Chase Bank, N.A. and U.S. Bank National Association |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  | $ 90,000,000.0 |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 1.79% |  |  |  |  |
San Juan Generating Station | PNM |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Request issuance of energy transition bonds |  |  |  |  |  |  | $ 361,000,000 |  |  |  |  |  |
San Juan Generating Station | PNM | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Request issuance of energy transition bonds |  |  |  | $ 361,000,000 |  |  |  |  |  |  |  |  |

X
- Definition Debt Instrument, Covenant, Debt To Capitalization Ratio + References No definition available. + Details
Name: | pnm_DebtInstrumentCovenantDebtToCapitalizationRatio
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Series Of Bond Issuance + References No definition available. + Details
Name: | pnm_DebtInstrumentSeriesOfBondIssuance
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Maturity term over which financings require regulator approval + References No definition available. + Details
Name: | pnm_PublicUtilitiesMaturitytermoverwhichfinancingsrequireregulatorapproval
Namespace Prefix: | pnm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Request Issuance Of Energy Transition Bonds + References No definition available. + Details
Name: | pnm_PublicUtilitiesRequestIssuanceOfEnergyTransitionBonds
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. + 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
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=114775744&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 Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870 Reference 2: 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=114775744&loc=d3e28551-108399 Reference 3: 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(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + 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 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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 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=109500613&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=119400593&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=6876686&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=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585 + Details
Name: | us-gaap_RepaymentsOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=pnm_PNMR2020ForwardEquitySalesAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNMR2016TwoYearTermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_PNMR2019TermLoanMember
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: | dei_LegalEntityAxis=pnm_PublicServiceCompanyOfNewMexicoMember
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: | srt_RangeAxis=srt_MaximumMember
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_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_Letterorcredit30milJPMorganMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementBondSeries1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementBondSeries2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementBondSeries3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementBondSeries4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementBondSeries1And2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_TNMP2020BondPurchaseAgreementBondSeries3And4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_SeniorUnsecuredNotes321SeriesADueApril2030Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=pnm_SeniorUnsecuredNotes357SeriesBDueApril2039Member
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_PNM2019TermLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=pnm_JPMorganChaseBankN.A.andU.S.BankNationalAssociationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=pnm_SanJuanGeneratingStationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |