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	6 Months Ended	9 Months Ended	12 Months Ended
	Oct. 03, 2022 USD ($)	Sep. 08, 2022	Aug. 23, 2022	Jul. 29, 2022 USD ($)	Jul. 19, 2022 MW	Jun. 17, 2022 USD ($)	Mar. 18, 2022 MW	Feb. 17, 2022 MW	Apr. 02, 2021 lease MW	Feb. 03, 2021	Jan. 08, 2021 USD ($)	Nov. 01, 2020 USD ($)	Jun. 29, 2020	Feb. 21, 2020 USD ($) numberOfAMIMeter	Jul. 10, 2019 proceeding	Jul. 01, 2019 USD ($)	Nov. 15, 2015 power_purchase_agreement numberOfAMIMeter batteryStorageAgreement	Jun. 30, 2022 MW	Nov. 30, 2020 USD ($)	Sep. 30, 2022 USD ($) MW	Dec. 31, 2021 USD ($) MW power_purchase_agreement	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($) MW power_purchase_agreement replacementResource	Sep. 02, 2022 MW	Feb. 14, 2022 MW	Dec. 18, 2020 USD ($)	Nov. 13, 2020 MW	Sep. 28, 2020 USD ($)	Jul. 29, 2020 MW	Mar. 31, 2020 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory time frame for proposed PPAs and battery storage agreements									6 months
Number of purchase power agreements | power_purchase_agreement																					3
Number of replacement resources | replacementResource																							4
Regulatory assets																				$ 820,832	$ 514,258	$ 820,832	$ 514,258
Regulatory liabilities																				772,355	841,393	772,355	$ 841,393
COVID-19
Public Utilities, General Disclosures [Line Items]
Temporary mandatory moratorium on disconnection period										100 days
Disconnection transition period										90 days
PNM
Public Utilities, General Disclosures [Line Items]
Regulatory disallowance and restructuring costs																						1,600
Solar generation capacity (in megawatts) | MW																													650
Number of megawatts in battery storage facilities (in megawatts) | MW																													300
Total number of agreements | numberOfAMIMeter																	5
Filing period, extension		2 days	45 days
Filing period, with extension		12 days
Number of days to file application													60 days
Payments for legal settlements				$ 19,800
Number of leases under which lease term was extended | lease									5
Number of purchase power agreements | power_purchase_agreement																	2						3
Number of battery storage agreements | batteryStorageAgreement																	3
Number of megawatts available in purchase power agreement (in megawatts) | MW							65	327										35
Number of megawatts, peak during period (in megawatts) | MW					2,071
Regulatory assets																				740,175	428,981	740,175	$ 428,981
Regulatory liabilities																				$ 571,483	653,830	$ 571,483	653,830
PNM | Subsequent event
Public Utilities, General Disclosures [Line Items]
Grid modernization investment	$ 344,000
Grid modernization, initial term	6 years
Grid modernization term	11 years
PNM | Minimum
Public Utilities, General Disclosures [Line Items]
Reserve margin							20.70%	17.40%												9.50%		0.90%
PNM | Maximum
Public Utilities, General Disclosures [Line Items]
Reserve margin							12.50%	9.80%												4.90%		3.40%
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
Initial payment for relief from obligations																			$ 15,000
PNM | Four Corners | PNM
Public Utilities, General Disclosures [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners												13.00%
PNM | COVID-19 | COVID-19 Costs Savings
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities																				$ 900	900	$ 900	900
PNM | Deferred COVID-19 Costs | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory assets																				$ 5,700	$ 6,900	5,700	$ 6,900
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		200
Number of megawatts in battery storage facilities (in megawatts) | MW									40																40		100
PNM | Replacement Resource Portfolio Two
Public Utilities, General Disclosures [Line Items]
Solar generation capacity (in megawatts) | MW																											100
Number of megawatts in battery storage facilities (in megawatts) | MW									100																100		30
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 | Portfolio One
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW																				125	85		85
PNM | Portfolio Two
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW																				35	150		150
PNM | Portfolio Three
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW																				40	40		40
PNM | Transportation Electrification Program
Public Utilities, General Disclosures [Line Items]
Expected budgeted expenditures																										$ 8,400
Budget flexibility																										25.00%
Budget portion dedicated to low and moderate income customers																										25.00%
San Juan Generating Station
Public Utilities, General Disclosures [Line Items]
Severance costs																						2,200
Obligations to fund severance																				$ 8,900		8,900
Estimated costs of replacement resources																												$ 8,100
San Juan Generating Station | Other deferred credits
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																				37,300	$ 36,900	37,300	$ 36,900
San Juan Generating Station | Employee Severance
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																				7,600		7,600								$ 9,400
San Juan Generating Station | PNM
Public Utilities, General Disclosures [Line Items]
Request issuance of energy transition bonds																$ 361,000
Forecasted undepreciated investment														$ 361,000		283,000
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 | numberOfAMIMeter														2
San Juan Generating Station | PNM | Other deferred credits
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																					36,000		36,000
San Juan Generating Station | PNM | Deferred Regulatory Asset
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																					$ 36,900		$ 36,900
San Juan Generating Station | PNM | Employee Severance
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																				$ 7,200		$ 7,200								8,100
San Juan Generating Station | PNM | Other Restructuring
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																														8,900
San Juan Generating Station | PNM | Economic Development and Workforce Training Costs
Public Utilities, General Disclosures [Line Items]
Restructuring reserve																														$ 19,800
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