Regulatory and Rate Matters - PNM (Details) $ in Millions							3 Months Ended
	Apr. 17, 2023 USD ($) program	Apr. 15, 2023 USD ($) GWh	Jan. 03, 2023 USD ($)	Dec. 05, 2022 USD ($) MW	Jun. 01, 2021 USD ($)	Apr. 15, 2020 USD ($) MMBTU program	Mar. 31, 2023 USD ($) lease $ / MWh MW	Mar. 31, 2022 USD ($)	Dec. 31, 2022 GWh	Jul. 29, 2020 MW
Public Utilities, Commitments And Contingencies [Line Items]
Excess return on jurisdictional equity that would require refund							0.50%
Return on equity							10.173%
Approved return on equity							10.075%
Allowed return on equity							9.575%
Allowed return on equity, additional							0.50%
PNM
Public Utilities, Commitments And Contingencies [Line Items]
Approved equity capital structure							52.00%
Approved debt capital structure							48.00%
Number of leases renewed | lease							5
Number of megawatts purchased (in megawatts) | MW							64.1
Non-recurring costs			$ 98.3
Solar generation capacity (in megawatts) | MW										650
Renewable Portfolio Standard | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Number of megawatts of Solar PV facilities | MW							158
Current output in the geothermal facility (in megawatts) | MW							11
Solar generation capacity (in megawatts) | MW							250.1
Energy Efficiency and Load Management Program | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Program costs related to energy efficiency, number of programs | program						12
Program costs related to energy efficiency, in year one						$ 31.4
Program costs related to energy efficiency, in year two						31.0
Program costs related to energy efficiency, in year three						$ 29.6
Energy efficiency and load management programs targeted energy savings (in Gigawatts) | MMBTU						94
2024 Plan | PNM | Subsequent event
Public Utilities, Commitments And Contingencies [Line Items]
Program costs related to energy efficiency, number of programs | program	10
Program costs related to energy efficiency, in year one	$ 34.5
Program costs related to energy efficiency, in year two	35.4
Program costs related to energy efficiency, in year three	$ 36.5
Integrated Resource Plan, 2011 | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Frequency of IRP filings							3 years
Planning period covered of IRP							20 years
NM 2022 Rate Case | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Recovery of base rate				$ 2,700.0
Revenue deficiency driver, years of operation				6 years
Leased PVNGS capacity, expiration | MW				114
Request suspension period				9 months
NM 2022 Rate Case | PNM | Non-Fuel Energy
Public Utilities, Commitments And Contingencies [Line Items]
Requested rate increase (decrease)				$ 63.8
NMPRC
Public Utilities, Commitments And Contingencies [Line Items]
Requested return on equity				10.25%
Action plan, covered period							4 years
NMPRC | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Proposed revision to rider that will allow for recovery					$ 61.0
NMPRC | Renewable Energy Rider | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Recorded revenues from renewable rider							$ 18.6	$ 14.5
Minimum | Renewable Portfolio Standard | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Energy efficiency and load management programs targeted energy savings (in Gigawatts) | MMBTU						80
Minimum | Energy Efficiency and Load Management Program | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Profit incentive sliding scale multiplier						0.071
Minimum | Energy Efficiency and Load Management Program | PNM | Subsequent event
Public Utilities, Commitments And Contingencies [Line Items]
Profit incentive sliding scale multiplier	0.071
Maximum | Renewable Portfolio Standard | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Reasonable cost threshold in megawatts per hour | $ / MWh							60
Maximum | Energy Efficiency and Load Management Program | PNM | Subsequent event
Public Utilities, Commitments And Contingencies [Line Items]
Profit incentive sliding scale multiplier	0.1073
New Mexico Wind | Renewable Portfolio Standard 2014 | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Number of megawatts for wind energy | MW							200
Red Mesa Wind | Renewable Portfolio Standard 2014 | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Number of megawatts for wind energy | MW							102
La Joya Wind | Renewable Portfolio Standard | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Number of megawatts for wind energy | MW							140
Disincentives and Incentives Added | 2020 Energy Efficiency Annual Report | PNM
Public Utilities, Commitments And Contingencies [Line Items]
Energy efficiency and load management programs additional incentive targeted energy savings (in Gigawatts) | GWh									94
Disincentives and Incentives Added | 2020 Energy Efficiency Annual Report | PNM | Subsequent event
Public Utilities, Commitments And Contingencies [Line Items]
Energy efficiency and load management programs additional incentive targeted energy savings (in Gigawatts) | GWh		94
Disincentives and Incentives Added | 2021 Energy Efficiency Annual Report | PNM | Subsequent event
Public Utilities, Commitments And Contingencies [Line Items]
Energy efficiency and load management programs		$ 0.3