Regulatory and Rate Matters - SJGS, Fours Corners and PVNGS Leased Interest Abandonment Applications (Details) $ in Thousands											1 Months Ended		3 Months Ended	6 Months Ended		12 Months Ended
	Jul. 29, 2022 USD ($)	Jul. 12, 2022 MW power_purchase_agreement	Jun. 17, 2022 USD ($)	Mar. 18, 2022 MW	Feb. 17, 2022 MW	Apr. 02, 2021 lease MW	Feb. 03, 2021	Jan. 08, 2021 USD ($)	Nov. 01, 2020 USD ($)	Jul. 01, 2019 USD ($)	Jun. 30, 2022 USD ($) MW	Nov. 30, 2020 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($) MW power_purchase_agreement	Dec. 31, 2021 USD ($) MW power_purchase_agreement	Feb. 14, 2022 MW	Dec. 18, 2020 USD ($)	Nov. 13, 2020 MW	Sep. 28, 2020 USD ($)	Jul. 29, 2020 MW	Mar. 31, 2020 USD ($)	Feb. 21, 2020 USD ($)
Public Utilities, General Disclosures [Line Items]
Number of purchase power agreements | power_purchase_agreement															3
Regulatory time frame for proposed PPAs and battery storage agreements						6 months
Regulatory assets											$ 599,052		$ 599,052	$ 599,052	$ 514,258	$ 514,258
Regulatory liabilities											$ 828,515		828,515	828,515	841,393	$ 841,393
Subsequent event
Public Utilities, General Disclosures [Line Items]
Number of purchase power agreements | power_purchase_agreement		3
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													1,400	1,400
Solar generation capacity (in megawatts) | MW																					650
Number of megawatts in battery storage facilities (in megawatts) | MW																					300
Number of purchase power agreements | power_purchase_agreement																3
Number of megawatts available in purchase power agreement (in megawatts) | MW				65	327						35
Number of leases under which lease term was extended | lease						5
Regulatory assets											$ 515,818		515,818	515,818	428,981	$ 428,981
Regulatory liabilities											629,466		629,466	$ 629,466	$ 653,830	653,830
PNM | Subsequent event
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW		125
Payments for legal settlements	$ 19,800
PNM | Minimum
Public Utilities, General Disclosures [Line Items]
Reserve margin				20.70%	17.40%									0.90%
PNM | Minimum | Subsequent event
Public Utilities, General Disclosures [Line Items]
Reserve margin		7.50%
PNM | Maximum
Public Utilities, General Disclosures [Line Items]
Reserve margin				12.50%	9.80%									3.40%
PNM | Maximum | Subsequent event
Public Utilities, General Disclosures [Line Items]
Reserve margin		2.90%
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
Number of megawatts available in purchase power agreement (in megawatts) | MW															35
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	900
PNM | Deferred COVID-19 Costs | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory assets											6,300		6,300	6,300	$ 6,900	$ 6,900
PNM | NMPRC
Public Utilities, General Disclosures [Line Items]
Solar generation capacity, amount requested for approval to abandon (in megawatts) | MW						114
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											150
PNM | Portfolio One
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW															85	85
PNM | Portfolio Two
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW															150	150
PNM | Portfolio Three
Public Utilities, General Disclosures [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) | MW															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														8,900
Estimated costs of replacement resources																				$ 8,100
San Juan Generating Station | Other deferred credits
Public Utilities, General Disclosures [Line Items]
Restructuring reserve											36,900		36,900	36,900	$ 36,900	$ 36,900
San Juan Generating Station | Employee Severance
Public Utilities, General Disclosures [Line Items]
Restructuring reserve											28,600		28,600	28,600								$ 9,400
San Juan Generating Station | PNM
Public Utilities, General Disclosures [Line Items]
Request issuance of energy transition bonds										$ 361,000
Forecasted undepreciated investment										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
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											$ 27,700		$ 27,700	$ 27,700								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