Regulatory and Rate Matters - SJGS Abandonment Application (Details) $ in Millions					12 Months Ended
	Jul. 29, 2022 USD ($)	Jun. 17, 2022 USD ($)	Jul. 10, 2019 proceeding	Jul. 01, 2019 USD ($)	Dec. 31, 2022 USD ($)	Oct. 14, 2022 MW	Dec. 31, 2021 USD ($)	Jul. 29, 2020 MW	Mar. 31, 2020 USD ($)	Mar. 30, 2020 USD ($)	Feb. 21, 2020 USD ($)
Public Service Company of New Mexico
Public Utilities, General Disclosures [Line Items]
Regulatory disallowance and festructuring costs					$ 1.6
Solar distributed generation (in mw) | MW						200		650
Number of megawatts in battery storage facilities (in megawatts) | MW						100		300
Payments for legal settlements	$ 19.8
Public Utilities, Loss Contingency					28.7
San Juan Generating Station
Public Utilities, General Disclosures [Line Items]
Severance costs					6.6
Severance					8.9
San Juan Generating Station | Other deferred credits
Public Utilities, General Disclosures [Line Items]
Restructuring reserve					37.2		$ 36.9
San Juan Generating Station | Employee Severance
Public Utilities, General Disclosures [Line Items]
Restructuring reserve					0.7				$ 9.4
San Juan Generating Station | Public Service Company of New Mexico
Public Utilities, General Disclosures [Line Items]
Request issuance of energy transition bonds				$ 361.0
Forecasted undepreciated investment					283.0						$ 361.0
Plant decommissioning and coal mine reclamation costs					28.6
Upfront financing costs					9.6
Severance costs					20.0
Proceeds from securitization bonds				$ 19.8
Number of proceedings | proceeding			2
San Juan Generating Station | Public Service Company of New Mexico | Other deferred credits
Public Utilities, General Disclosures [Line Items]
Restructuring reserve							36.0
San Juan Generating Station | Public Service Company of New Mexico | Deferred Regulatory Asset
Public Utilities, General Disclosures [Line Items]
Restructuring reserve							$ 36.9
San Juan Generating Station | Public Service Company of New Mexico | Employee Severance
Public Utilities, General Disclosures [Line Items]
Restructuring reserve									$ 8.1
San Juan Generating Station | Public Service Company of New Mexico | Other Restructuring
Public Utilities, General Disclosures [Line Items]
Restructuring reserve										$ 8.9
San Juan Generating Station | Public Service Company of New Mexico | Economic Development and Workforce Training Costs
Public Utilities, General Disclosures [Line Items]
Restructuring reserve					$ 19.8					$ 19.8
San Juan Generation Station, Unit 1 | Public Service Company of New Mexico
Public Utilities, General Disclosures [Line Items]
Annual rate credits		$ 21.1
San Juan Generating Station, Unit 4 | Public Service Company of New Mexico
Public Utilities, General Disclosures [Line Items]
Annual rate credits		$ 98.3
Number of days to transfer payment		30 days