Regulatory and Rate Matters - SJGS Abandonment Application, Fours Corners, PVNGS Leased Interest Abandonment Application, Summer Peak Resource Adequacy, COVID and Transportation Electrification Program (Details) $ in Thousands														1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 30, 2023 MW	Dec. 05, 2022 MW	Oct. 03, 2022 USD ($)	Sep. 08, 2022	Jul. 29, 2022 USD ($)	Jul. 19, 2022 MW	Jun. 17, 2022 USD ($)	Apr. 02, 2021 lease MW	Jan. 08, 2021 USD ($)	Nov. 01, 2020 USD ($)	Jul. 10, 2019 proceeding	Jul. 01, 2019 USD ($)	Nov. 15, 2015 power_purchase_agreement batteryStorageAgreement numberOfAMIMeter	Nov. 30, 2020 USD ($)	Mar. 31, 2023 USD ($) MW	Dec. 31, 2021 power_purchase_agreement replacementResource	Dec. 31, 2022 USD ($)	Sep. 02, 2022 MW	Feb. 14, 2022 MW	Jul. 29, 2020 MW	Feb. 21, 2020 USD ($)
Public Utilities, General Disclosures [Line Items]
Decrease in undepreciated leasehold improvements															$ 88,200
Increase in deferred regulatory assets															88,200
Regulatory time frame for proposed PPAs and battery storage agreements								6 months
Number of replacement resources | replacementResource																4
Regulatory assets															933,713		$ 846,686
Regulatory liabilities															756,561		755,202
PNM
Public Utilities, General Disclosures [Line Items]
Solar generation capacity (in megawatts) | MW																				650
Number of megawatts in battery storage facilities (in megawatts) | MW																				300
Filing period, extension				2 days
Filing period, with extension				12 days
Payments for legal settlements					$ 19,800
Number of leases under which lease term was extended | lease								5
Potential loss on rate change															8,700
Total number of agreements | numberOfAMIMeter													5
Number of purchase power agreements | power_purchase_agreement													2			3
Number of battery storage agreements | batteryStorageAgreement													3
Number of megawatts, peak during period (in megawatts) | MW						2,139
Grid modernization investment			$ 344,000
Grid modernization, initial term			6 years
Grid modernization term			11 years
Regulatory assets															850,860		763,941
Regulatory liabilities															557,564		556,989
Loss contingency															$ 53,200
PNM | Minimum
Public Utilities, General Disclosures [Line Items]
Reserve margin															11.00%
PNM | Maximum
Public Utilities, General Disclosures [Line Items]
Reserve margin															16.00%
PNM | Four Corners
Public Utilities, General Disclosures [Line Items]
Request issuance of energy transition bonds									$ 300,000
Forecasted undepreciated investment									272,000
Plant decommissioning and coal mine reclamation costs									4,600
Upfront financing costs									7,300
Proceeds from securitization bonds									$ 16,500
Payments for relief from obligations										$ 75,000				$ 15,000
Final payment for relief from obligations														$ 60,000
PNM | Four Corners | PNM
Public Utilities, General Disclosures [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners										13.00%
PNM | Deferred COVID-19 Costs | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory assets															$ 5,700
Regulatory liabilities															$ 900		$ 900
PNM | Leased Interest Termination on January 15, 2023
Public Utilities, General Disclosures [Line Items]
Number of leases under which lease term was extended | lease								4
PNM | Leased Interest Termination on January 15, 2023 | NMPRC
Public Utilities, General Disclosures [Line Items]
Solar generation capacity (in megawatts) | MW								104
PNM | Leased Interest Termination on January 15, 2024 | NMPRC
Public Utilities, General Disclosures [Line Items]
Solar generation capacity (in megawatts) | MW								10
PNM | Replacement Resource Portfolio One
Public Utilities, General Disclosures [Line Items]
Solar generation capacity (in megawatts) | MW								150											150
Number of megawatts in battery storage facilities (in megawatts) | MW								40											40
PNM | Replacement Resource Portfolio Two
Public Utilities, General Disclosures [Line Items]
Number of megawatts in battery storage facilities (in megawatts) | MW								100											100
PNM | Replacement Resource Portfolio Three
Public Utilities, General Disclosures [Line Items]
Solar generation capacity (in megawatts) | MW								300											300
Number of megawatts in battery storage facilities (in megawatts) | MW								150										300	150
PNM | Solar Agreement
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW	100
PNM | Battery Storage Agreement
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW	30
PNM | NM 2022 Rate Case
Public Utilities, General Disclosures [Line Items]
Megawatt repurchase | MW		64.1
PNM | Firm Power Purchases
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW															420
PNM | Firm Capacity
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW															40
San Juan Generating Station | PNM
Public Utilities, General Disclosures [Line Items]
Request issuance of energy transition bonds												$ 361,000
Forecasted undepreciated investment												283,000									$ 361,000
Plant decommissioning and coal mine reclamation costs												28,600
Upfront financing costs												9,600
Severance costs												20,000
Proceeds from securitization bonds												$ 19,800
Number of proceedings | proceeding											2
Number of recommendations | proceeding											1
San Juan Generation Station, Unit 1 | PNM
Public Utilities, General Disclosures [Line Items]
Annual rate credits							$ 21,100
San Juan Generating Station, Unit 4 | PNM
Public Utilities, General Disclosures [Line Items]
Annual rate credits							$ 98,300
Number of days to transfer payment							30 days