XML 75 R56.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Commitments and Contingencies - Royalty Rates, Tax Assessment, Insurance and Other Matters (Details) | Sep. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 01, 2015 Allotment_Parcel | Jul. 13, 2015 a | Jan. 22, 2015 Allotment_Parcel | Apr. 02, 2014 landowner Allotment_Parcel | Jan. 06, 2014 Allotment_Parcel | Aug. 31, 2013 | May 23, 2013 USD ($) | Sep. 30, 2012 landowner
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Palo Verde Nuclear Generating Station [Member] | Public Service Company of New Mexico [Member] | Nuclear Plant [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Ownership percentage in nuclear reactor | 10.20% |  |  |  |  |  |  |  |  |
Maximum potential assessment per incident | $ 38,900,000.0 |  |  |  |  |  |  |  |  |
Annual payment limitation related to incident | 5,800,000.0 |  |  |  |  |  |  |  |  |
Aggregate amount of all risk insurance | 2,750,000,000.00 |  |  |  |  |  |  |  |  |
Maximum amount under Nuclear Electric Insurance Limited | 5,400,000.0 |  |  |  |  |  |  |  |  |
Palo Verde Nuclear Generating Station [Member] | Public Service Company of New Mexico [Member] | Nuclear Plant [Member] | Commercial Providers [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Liability insurance coverage | 375,000,000 |  |  |  |  |  |  |  |  |
Palo Verde Nuclear Generating Station [Member] | Public Service Company of New Mexico [Member] | Nuclear Plant [Member] | Industry Wide Retrospective Assessment Program [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Liability insurance coverage | 13,100,000,000.0 |  |  |  |  |  |  |  |  |
Palo Verde Nuclear Generating Station [Member] | Public Service Company of New Mexico [Member] | Nuclear Plant [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Liability insurance coverage | 13,500,000,000.0 |  |  |  |  |  |  |  |  |
Liability insurance coverage sublimit | $ 2,250,000,000.00 |  |  |  |  |  |  |  |  |
Continuous Highwall Mining [Member] | San Juan Generating Station [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Proposed retroactive surface mining royalty rate |  |  |  |  |  |  |  | 12.50% |  |
Surface mining royalty rate applied | 8.00% |  |  |  |  |  |  |  |  |
Estimated underpaid surface mining royalties under proposed rate change | $ 5,000,000 |  |  |  |  |  |  |  |  |
PNM's share estimated underpaid surface mining royalties under proposed rate change | 46.30% |  |  |  |  |  |  |  |  |
NMTRD Coal Severance Tax [Member] | Four Corners [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Assessed coal severance surtax, penalty and interest |  |  |  |  |  |  |  |  | $ 30,000,000 |
Share of settlement in addition to amounts previously paid |  | $ 100,000 |  |  |  |  |  |  |  |
Navajo Nation Allottee Matters [Member] | Public Service Company of New Mexico [Member] |  |  |  |  |  |  |  |  |  |
Public Utilities, Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |
Number of landowners claiming to be Navajo allottees (in landowners) | landowner |  |  |  |  |  | 43 |  |  |  | 43
Number of allotment parcels' appraisal requested for review (in allotment parcels) | Allotment_Parcel |  |  |  |  |  |  | 58 |  |  |
Number of allotments where landowners are revoking rights of way renewal consents (in allotment parcels) | Allotment_Parcel |  |  |  |  | 10 | 6 |  |  |  |
Area of land (in acres) | a |  |  |  | 15.49 |  |  |  |  |  |
Number of allotment parcels at issue that are not to be condemned | Allotment_Parcel |  |  | 2 |  |  |  |  |  |  |
Number of allotment parcels at issue | Allotment_Parcel |  |  | 5 |  |  |  |  |  |  |

X
- Definition Number of allotment parcels' appraisal requested for review + References No definition available. + Details
Name: | pnm_Numberofallotmentparcelsappraisalrequestedforreview
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of allotment parcels' at issue + References No definition available. + Details
Name: | pnm_Numberofallotmentparcelsatissue
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of allotment parcels' at issue, Not to be condemned + References No definition available. + Details
Name: | pnm_NumberofallotmentparcelsatissueNottobecondemned
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of allotments where landowners are revoking rights of way renewal consents + References No definition available. + Details
Name: | pnm_Numberofallotmentswherelandownersarerevokingrightsofwayrenewalconsents
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of landowners claiming to be Navajo allottees + References No definition available. + Details
Name: | pnm_NumberoflandownersclaimingtobeNavajoallottees
Namespace Prefix: | pnm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Aggregate Amount of All Risk Insurance + References No definition available. + Details
Name: | pnm_PublicUtilitiesAggregateAmountOfAllRiskInsurance
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Annual Payment Limitation Related to Incident + References No definition available. + Details
Name: | pnm_PublicUtilitiesAnnualPaymentLimitationRelatedToIncident
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Assessed Coal Severance Surtax Penalty and Interest + References No definition available. + Details
Name: | pnm_PublicUtilitiesAssessedCoalSeveranceSurtaxPenaltyandInterest
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Assessed Coal Severance Surtax Penalty and Interest, PNM Share + References No definition available. + Details
Name: | pnm_PublicUtilitiesAssessedCoalSeveranceSurtaxPenaltyandInterestPNMShare
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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, Current Surface Mining Royalty Rate applied between 2000 and 2003 + References No definition available. + Details
Name: | pnm_PublicUtilitiesCurrentSurfaceMiningRoyaltyRateappliedbetween2000and2003
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Estimated Underpaid Surface Mining Royalties under proposed rate change + References No definition available. + Details
Name: | pnm_PublicUtilitiesEstimatedUnderpaidSurfaceMiningRoyaltiesunderproposedratechange
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Liability Insurance Coverage + References No definition available. + Details
Name: | pnm_PublicUtilitiesLiabilityInsuranceCoverage
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Public Utilities, Liability Insurance Coverage Sublimit + References No definition available. + Details
Name: | pnm_PublicUtilitiesLiabilityInsuranceCoverageSublimit
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Maximum Amount under Nuclear Electric Insurance Limited + References No definition available. + Details
Name: | pnm_PublicUtilitiesMaximumAmountunderNuclearElectricInsuranceLimited
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Maximum Potential Assessment Per Incident + References No definition available. + Details
Name: | pnm_PublicUtilitiesMaximumPotentialAssessmentPerIncident
Namespace Prefix: | pnm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Ownership Percentage in Nuclear Reactor + References No definition available. + Details
Name: | pnm_PublicUtilitiesOwnershipPercentageInNuclearReactor
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, PNM Share Estimated Underpaid Surface Mining Royalties under proposed rate change + References No definition available. + Details
Name: | pnm_PublicUtilitiesPNMShareEstimatedUnderpaidSurfaceMiningRoyaltiesunderproposedratechange
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public Utilities, Proposed Retroactive Surface Mining Royalty Rate + References No definition available. + Details
Name: | pnm_PublicUtilitiesProposedRetroactiveSurfaceMiningRoyaltyRate
Namespace Prefix: | pnm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Area of land held. + References No definition available. + Details
Name: | us-gaap_AreaOfLand
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | pnm_InsuranceCarrierAxis=pnm_CommercialProvidersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnm_InsuranceCarrierAxis=pnm_IndustryWideRetrospectiveAssessmentProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_OtherCommitmentsAxis=pnm_ContinuousHighwallMiningMember
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: | us-gaap_OtherCommitmentsAxis=pnm_NMTRDCoalSeveranceTaxMember
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_OtherCommitmentsAxis=pnm_NavajoNationAllotteeMattersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |