Number of other parties to settlement

No definition available.

Name:	pnm_Numberofotherpartiestosettlement
Namespace Prefix:	pnm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage ownership of EIP transmission line

+ References

No definition available.

+ Details

Name:	pnm_PercentageOwnershipOfEipTransmissionLine
Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Annual Revenue To be Collected Under 2015 Rider Rate

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesAnnualRevenueTobeCollectedUnder2015RiderRate
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Public Utilities, Anticipated future profit incentive

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesAnticipatedfutureprofitincentive
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Public Utilities, Cost of replacement gas-generation

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesCostofreplacementgasgeneration
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Public Utilities, Energy Efficiency Targeted Savings, GWh

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesEnergyEfficiencyTargetedSavingsGWh
Namespace Prefix:	pnm_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Estimated Future Investment

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesEstimatedFutureInvestment
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Public Utilities, Estimated costs to be recovered

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesEstimatedcoststoberecovered
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Public Utilities, Expected average monthly usage in megawatts

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesExpectedaveragemonthlyusageinmegawatts
Namespace Prefix:	pnm_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Frequency of IRP filings

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesFrequencyofIRPfilings
Namespace Prefix:	pnm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Newly Identified Replacement Gas-fired Aeroderivative Generation, per Unit, in Megawatts

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesNewlyIdentifiedReplacementGasfiredAeroderivativeGenerationperUnitinMegawatts
Namespace Prefix:	pnm_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Newly Identified Replacement Gas-fired Generation, in Megawatts

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesNewlyIdentifiedReplacementGasfiredGenerationinMegawatts
Namespace Prefix:	pnm_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Number of Aeroderviative Gas-Generation Units

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesNumberofAeroderviativeGasGenerationUnits
Namespace Prefix:	pnm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Planning Period Covered of IRP

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesPlanningPeriodCoveredOfIrp
Namespace Prefix:	pnm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Program Costs Related To Energy Efficiency

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesProgramCostsRelatedToEnergyEfficiency
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reasonable Cost Threshold

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesReasonableCostThreshold
Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Regulated Operations, Required Percentage of Diversification

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesRequiredPercentageOfDiversification
Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Regulated Operations, Required Percentage of Renewable Energy in Portfolio to Electric Sales

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesRequiredPercentageOfRenewableEnergyInPortfolioToElectricSales
Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Return on Equity

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesReturnonEquity
Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Public Utilities, Revenue For Power Sold Under Specific Contract

+ References

No definition available.

+ Details

Name:	pnm_PublicUtilitiesRevenueForPowerSoldUnderSpecificContract
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of regulatory costs not yet approved by the regulatory authority.

+ References

No definition available.

+ Details

Name:	us-gaap_AmountOfRegulatoryCostsNotYetApproved
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=pnm_PublicServiceCompanyOfNewMexicoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_CommitmentsAndContingenciesRelatedToEnvironmentAndOtherNatureAxis=pnm_CleanAirActSncrMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_JointlyOwnedUtilityPlantAxis=pnm_SanJuanGeneratingStationUnits2And3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_A2015ElectricRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_RenewablePortfolioStandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	pnm_DiversificationByTypeAxis=pnm_WindEnergyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_DiversificationByTypeAxis=pnm_SolarEnergyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_DiversificationByTypeAxis=pnm_DistributedGenerationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_DiversificationByTypeAxis=pnm_RenewableTechnologiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_DateOfRegulatoryActionAxis=pnm_RequiredPercentageBy2011Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_DateOfRegulatoryActionAxis=pnm_RequiredPercentageBy2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_DateOfRegulatoryActionAxis=pnm_RequiredPercentageBy2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_RenewableEnergyRiderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_A2017EnergyEfficiencyandLoadManagementProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	pnm_TypeOfRegulatoryCostAxis=pnm_DisincentivesIncentivesAdderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_IntegratedResourcePlan2011Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_AdvancedmeteringinfrastructureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_FormulaTransmissionRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pnm_ScheduleOfRegulatoryRateMattersAxis=pnm_FirmRequirementsWholesalePowerRateCaseNavopacheMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Regulatory and Rate Matters - PNM (Details) - Public Service Company of New Mexico [Member] $ in Millions				3 Months Ended		12 Months Ended
	Apr. 16, 2016 USD ($)	Aug. 27, 2015 USD ($)	Mar. 20, 2015 USD ($) party	Mar. 31, 2016 USD ($) turbine MW	Mar. 31, 2015 USD ($)	Dec. 31, 2015	Apr. 15, 2016 USD ($) GWh	Jun. 30, 2015 MW	Dec. 31, 2013	Mar. 01, 2013	Dec. 31, 2012 USD ($)
Clean Air Act, SNCR [Member] \| San Juan Generating Station Units 2 and 3 [Member]
Public Utilities, General Disclosures [Line Items]
Newly identified replacement gas-fired generation (in megawatts) \| MW				80				187
Number of aeroderviative units (in turbines) \| turbine				2
Replacement gas-fired aeroderivative generation (in megawatts) \| MW				40
Cost of replacement gas-fired unit				$ 86.8
2015 Electric Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease)		$ 123.5
Requested return on equity		10.50%
Renewable Portfolio Standard [Member] \| Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Reasonable cost threshold				3.00%					3.00%
Renewable Portfolio Standard [Member] \| Wind Energy [Member] \| Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of diversification				30.00%
Renewable Portfolio Standard [Member] \| Solar Energy [Member] \| Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of diversification				20.00%
Renewable Portfolio Standard [Member] \| Distributed Generation [Member] \| Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of diversification				3.00%
Renewable Portfolio Standard [Member] \| Renewable Technologies [Member] \| Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of diversification				5.00%
Renewable Portfolio Standard [Member] \| Required Percentage by 2011 [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of renewable energy in portfolio to electric sales				10.00%
Renewable Portfolio Standard [Member] \| Required Percentage by 2015 [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of renewable energy in portfolio to electric sales				15.00%
Renewable Portfolio Standard [Member] \| Required Percentage by 2020 [Member]
Public Utilities, General Disclosures [Line Items]
Required percentage of renewable energy in portfolio to electric sales				20.00%
Renewable Energy Rider [Member] \| Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity				10.50%		10.50%
Proposal to collect funds under renewable energy procurement plan				$ 42.4
2017 Energy Efficiency and Load Management Program [Member] \| Subsequent Event [Member] \| Disincentives / Incentives Adder [Member]
Public Utilities, General Disclosures [Line Items]
Program portfolio's total budget	$ 28.0
Incentive based on target savings							$ 2.4
Targeted savings (in gigawatt hours) \| GWh							75
Integrated Resource Plan, 2011 [Member]
Public Utilities, General Disclosures [Line Items]
Frequency of IRP filings				3 years
Planning period covered of IRP				20 years
Advanced Metering Infrastructure Costs [Member]
Public Utilities, General Disclosures [Line Items]
Estimated costs to be recovered				$ 87.2
Estimated future investment				$ 33.0
Formula Transmission Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Amount of regulatory costs not yet approved											$ 3.2
Return on equity			10.00%								10.81%
Percentage ownership of EIP transmission line										60.00%
Number of other parties entered into settlement agreement \| party			5
Approved rate increase (decrease)			$ 1.3
Firm Requirements Wholesale Power Rate Case, Navopache [Member] [Member]
Public Utilities, General Disclosures [Line Items]
Number of megawatts served under a short-term coordination tariff \| MW				10
Revenues from NEC				$ 5.4	$ 7.1