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Contract With Customer, Liability, Net Exposure

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Contract With Customer, Net Liability Position

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(Increase)/Decrease In Other Than Temporary Losses, Investments, Portion Recognized In Earnings, Net, Available-For-Sale Securities

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Public Utilities, Number Of Megawatts Available In Purchase Power Agreement

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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The amount of cash or securities placed with a broker or counterparty as security for a trading or derivatives securities position which was partially obtained with funds provided by the broker dealer.

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Fair Value of Derivative and Other Financial Instruments - Narrative (Details)	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Apr. 30, 2025 MW	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) MW
Debt Securities, Available-for-sale [Line Items]
Obligations to return cash	$ 0			$ 0		$ 0
Public Service Company of New Mexico
Debt Securities, Available-for-sale [Line Items]
Contractual liability	0			0		5,700,000
Cash collateral	0			0		0
Net liability position	0			0		5,700,000
Amounts recognized for right to reclaim cash	0			0		0
Cash collateral under margin arrangements	0			0		100,000
Available-for-sale debt securities	44,804,000			44,804,000
(Increase)/decrease in other than temporary losses of available-for-sale securities, net portion recognized in earnings	0	$ 2,000,000.0		0	$ 17,000,000.0
Public Service Company of New Mexico \| Recurring
Debt Securities, Available-for-sale [Line Items]
Available-for-sale debt securities	430,292,000			430,292,000		453,421,000
Public Service Company of New Mexico \| Recurring \| Nuclear Decommissioning Trust
Debt Securities, Available-for-sale [Line Items]
Available-for-sale debt securities	420,800,000			420,800,000		384,600,000
Public Service Company of New Mexico \| Recurring \| SJGS Decommissioning Trust
Debt Securities, Available-for-sale [Line Items]
Available-for-sale debt securities	2,300,000			2,300,000		8,200,000
Public Service Company of New Mexico \| Recurring \| Mine Reclamation Trust
Debt Securities, Available-for-sale [Line Items]
Available-for-sale debt securities	$ 70,800,000			$ 70,800,000		$ 82,700,000
Portfolio One \| Public Service Company of New Mexico
Debt Securities, Available-for-sale [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) \| MW			250			150
Portfolio Two \| Public Service Company of New Mexico
Debt Securities, Available-for-sale [Line Items]
Number of megawatts available in purchase power agreement (in megawatts) \| MW						100