XML 144 R119.htm IDEA: XBRL DOCUMENT v3.10.0.1

Regulatory and Rate Matters - TNMP Schedules (Details) - Texas-New Mexico Power Company - USD ($) $ in Millions						12 Months Ended
	Mar. 27, 2018	Sep. 13, 2017	Mar. 14, 2017	Sep. 08, 2016	Mar. 23, 2016	Feb. 29, 2020	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2017
Energy efficiency costs
Public Utilities, General Disclosures [Line Items]
Aggregate Collection Amount								$ 6.0	$ 6.0
Performance Bonus								$ 0.8	$ 0.7
Energy efficiency costs | Scenario, forecast
Public Utilities, General Disclosures [Line Items]
Aggregate Collection Amount						$ 5.6	$ 6.0
Performance Bonus						$ 0.8	$ 1.1
Transmission Cost of Service Rates
Public Utilities, General Disclosures [Line Items]
Approved Increase in Rate Base	$ 32.0	$ 27.5	$ 30.2	$ 9.5	$ 25.8
Annual Increase in Revenue	$ 0.6	$ 4.7	$ 4.8	$ 1.8	$ 4.3

X

- Definition

Public Utilities, Approved Cost Recovery Factor, Performance Bonus

+ References

No definition available.

+ Details

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

X

- Definition

Public Utilities, Approved Cost Recovery Factor, Program Costs

+ References

No definition available.

+ Details

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

X

- Definition

Public Utilities, Increase Annual Transmission Service Revenue

+ References

No definition available.

+ Details

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

X

- 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

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

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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