XML 81 R59.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Commitments and Contingencies - Coal Supply (Details) |  |  | 3 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Feb. 01, 2016 USD ($) | Jan. 31, 2016 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Apr. 20, 2018 USD ($) | Feb. 01, 2018 | Oct. 20, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Jun. 29, 2017 USD ($) | Feb. 01, 2017 | Dec. 31, 2016 USD ($) | Aug. 01, 2016 payment | Dec. 31, 2015 USD ($)
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other current assets |  |  | $ 46,389,000 | $ 47,358,000 |  |  |  |  |  |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other current assets |  |  | 41,607,000 | 39,904,000 |  |  |  |  |  |  |  |  |  |
Amount held in a restricted bank account |  |  |  |  |  |  |  |  |  | $ 1,000,000 |  | $ 7,200,000 |  | $ 8,200,000
PNM | Surface |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  | 100,000,000 |  |  |  |  |  |  |  |  |  |  |
PNM | Four Corners |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share of estimated shortfall payment |  |  |  |  |  |  |  | $ 11,600,000 | $ 6,500,000 |  |  |  |  |
PNM | Loss on long-term purchase commitment | Surface |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss contingency accrual |  |  | 41,200,000 | 41,400,000 |  |  |  |  |  |  |  |  |  |
Increase (decrease) for interim storage costs liability |  |  |  | 35,000,000 |  |  |  |  |  |  |  |  |  |
Final reclamation, capped amount to be collected |  |  | 100,000,000.0 |  |  |  |  |  |  |  |  |  |  |
PNM | Loss on long-term purchase commitment | Underground |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss contingency accrual |  |  | 15,100,000 | 14,700,000 |  |  |  |  |  |  |  |  |  |
Increase (decrease) for interim storage costs liability |  |  |  | 5,000,000 |  |  |  |  |  |  |  |  |  |
PNM | Loss on long-term purchase commitment | San Juan Generating Station | Surface |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimate of possible loss |  |  | 99,700,000 |  |  |  |  |  |  |  |  |  |  |
PNM | Loss on long-term purchase commitment | San Juan Generating Station | Underground |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimate of possible loss |  |  | 127,100,000 |  |  |  |  |  |  |  |  |  |  |
Coal supply | PNM | San Juan Generating Station |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other current assets |  |  | 26,300,000 | 26,300,000 |  |  |  |  |  |  |  |  |  |
Estimated increase in coal cost |  |  |  |  |  |  |  |  | 51.00% |  |  |  |  |
Coal supply | NM Capital | San Juan Generating Station |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to fund long-term loans to unaffiliated third party |  | $ 125,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Loan agreement among several entities |  | $ 125,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |
Interest rate |  | 7.25% |  |  |  | 12.25% |  |  |  |  | 9.25% |  |  |
Requirement to post reclamation bonds |  |  | 118,700,000 |  |  |  |  |  |  |  |  |  |  |
Cash used to support bank letter or credit arrangement |  | $ 30,300,000 | 30,300,000 |  |  |  |  |  |  |  |  |  |  |
Coal supply | NM Capital | San Juan Coal Company, Westmoreland |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to fund long-term loans to unaffiliated third party | $ 125,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |
Loan receivable |  | $ 125,000,000 | 51,000,000 |  |  |  |  |  |  |  |  |  |  |
Scheduled principal payment proceeds |  |  | 900,000 |  |  |  |  |  |  |  |  |  |  |
Scheduled interest payment proceeds |  |  | 1,800,000 |  |  |  |  |  |  |  |  |  |  |
Prepayment penalty |  |  | 0 |  |  |  |  |  |  |  |  |  |  |
Coal supply | Unaffiliated third party | San Juan Coal Company, Westmoreland |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount held in a restricted bank account |  |  |  |  |  |  | $ 2,700,000 |  |  |  |  |  |  |
BTMU Term Loan Agreement | NM Capital |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt | $ 125,000,000.0 |  | 45,100,000 |  |  |  |  |  |  |  |  |  |  |
Subsequent event | Coal supply | Unaffiliated third party | San Juan Coal Company, Westmoreland |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount held in a restricted bank account |  |  |  |  | $ 2,700,000 |  |  |  |  |  |  |  |  |
Mine Reclamation Trust | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required contribution to Reclamation Trust, current fiscal year |  |  | 7,500,000 |  |  |  |  |  |  |  |  |  |  |
Reclamation Trust Funding, Year 2 |  |  | 8,700,000 |  |  |  |  |  |  |  |  |  |  |
Reclamation Trust Funding, Year 3 |  |  | 9,200,000 |  |  |  |  |  |  |  |  |  |  |
San Juan Generating Station | Loss on long-term purchase commitment | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual funding post-term reclamation trust |  |  |  | $ 5,800,000 |  |  |  |  |  |  |  |  |  |
Four Corners | Mine Reclamation Trust | PNM |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required contribution to Reclamation Trust, current fiscal year |  |  | 2,300,000 |  |  |  |  |  |  |  |  |  |  |
Reclamation Trust Funding, Year 2 |  |  | 2,300,000 |  |  |  |  |  |  |  |  |  |  |
Reclamation Trust Funding, Year 3 |  |  | $ 2,100,000 |  |  |  |  |  |  |  |  |  |  |
Number of annual installment payments | payment |  |  |  |  |  |  |  |  |  |  |  |  | 13 |

X
- Definition Cash used to support bank letter or credit arrangement + References No definition available. + Details
Name: | pnm_Cashusedtosupportbankletterorcreditarrangement
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Coal Mine Reclamation Bonds to be posted with NMMMD + References No definition available. + Details
Name: | pnm_CoalMineReclamationBondstobepostedwithNMMMD
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Final Reclamation, capped amount to be collected + References No definition available. + Details
Name: | pnm_FinalReclamationCappedAmountToBeCollected
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Loan Receivable, Scheduled interest payment proceeds + References No definition available. + Details
Name: | pnm_LoanReceivableScheduledinterestpaymentproceeds
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Loan Receivable, Scheduled principal payment proceeds + References No definition available. + Details
Name: | pnm_LoanReceivableScheduledprincipalpaymentproceeds
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Payments to fund long-term loans to unaffiliated third party + References No definition available. + Details
Name: | pnm_Paymentstofundlongtermloanstounaffiliatedthirdparty
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Prepayment penalty + References No definition available. + Details
Name: | pnm_Prepaymentpenalty
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Annual Funding post-term reclamation trust + References No definition available. + Details
Name: | pnm_PublicUtilitiesAnnualFundingposttermreclamationtrust
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Commitments And Contingencies [Line Items] + References No definition available. + Details
Name: | pnm_PublicUtilitiesCommitmentsAndContingenciesLineItems
Namespace Prefix: | pnm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Estimated Increase in Coal Cost, Percentage + References No definition available. + Details
Name: | pnm_PublicUtilitiesEstimatedIncreaseinCoalCostPercentage
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Number of annual installment payments + References No definition available. + Details
Name: | pnm_PublicUtilitiesNumberofannualinstallmentpayments
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Reclamation Trust Funding, Current fiscal year + References No definition available. + Details
Name: | pnm_ReclamationTrustFundingCurrentfiscalyear
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reclamation Trust Funding, Year 2 + References No definition available. + Details
Name: | pnm_ReclamationTrustFundingYear2
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reclamation Trust Funding, Year 3 + References No definition available. + Details
Name: | pnm_ReclamationTrustFundingYear3
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at interest rates that increase or decrease depending on certain facts or circumstances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 825 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=75032840&loc=d3e61082-112788 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 825 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=75032840&loc=d3e61044-112788 + Details
Name: | us-gaap_LoansAndLeasesReceivableCommitmentsVariableRates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522 + Details
Name: | us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The percentage points (also referred to as 'margin') added to the reference rate as stated in the loan agreement and used to compute the variable rate on the loans receivable. For instance, the loan agreement might state that the interest rate the borrower is obligated to pay is the London Interbank Offered Rate (LIBOR) plus three quarters (3/4) of a percentage point adjusted quarterly (each three months). LIBOR in this example is the index or reference rate, 3/4 percentage point is the margin, the reference rate plus the margin is the fully indexed rate. This element would be used to report separately the margin. + References No definition available. + Details
Name: | us-gaap_LoansReceivableBasisSpreadOnVariableRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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/presentationRef -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=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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 3: http://www.xbrl.org/2003/role/presentationRef -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 Amount of loss contingency liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 + Details
Name: | us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase (decrease) in loss contingency liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 + Details
Name: | us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349 + Details
Name: | us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of current assets classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.8) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_OtherAssetsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_RegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3044-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(1)(a)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(2)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_RestrictedCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77896938&loc=d3e25336-109308 + Details
Name: | us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Details
Name: | pnm_ClassificationOfMineAxis=pnm_SurfaceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_LossOnLongTermPurchaseCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_ClassificationOfMineAxis=pnm_UndergroundMember
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: |

X
- Details
Name: | us-gaap_PurchaseCommitmentExcludingLongtermCommitmentAxis=pnm_CoalSupplyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

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

X
- Details
Name: | pnm_CommitmentsAndContingenciesRelatedToEnvironmentAndOtherNatureAxis=us-gaap_LossOnLongTermPurchaseCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_JointlyOwnedGeneratingFacilitiesAxis=pnm_FourCornersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |