Fair Value Measures and Disclosures - Gross Realized (Losses) (Details) - PNM - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales	$ 302,510	$ 91,211
Gross realized gains	13,679	3,428
Gross realized (losses)	$ (7,912)	$ (6,471)