Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Current federal income tax	$ 0	$ 0	$ 0
Current state income tax (benefit)	(2,841)	1,597	1,835
Deferred federal income tax (benefit)	(11,503)	18,413	20,679
Deferred state income tax (benefit)	(825)	7,302	11,315
Amortization of accumulated investment tax credits	(1,181)	(1,182)	(1,247)
Total income taxes (benefits)	(16,350)	26,130	32,582
PNM
Income Taxes [Line Items]
Current federal income tax	9,518	(13,533)	0
Current state income tax (benefit)	(4,304)	3,244	(128)
Deferred federal income tax (benefit)	(22,951)	25,298	18,774
Deferred state income tax (benefit)	1,150	4,361	8,583
Amortization of accumulated investment tax credits	(171)	(172)	(237)
Total income taxes (benefits)	(16,758)	19,198	26,992
TNMP
Income Taxes [Line Items]
Current federal income tax	11,354	17,055	5,770
Current state income tax (benefit)	3,055	2,662	2,395
Deferred federal income tax (benefit)	2,917	(4,527)	(224)
Deferred state income tax (benefit)	(29)	(29)	(29)
Total income taxes (benefits)	$ 17,297	$ 15,161	$ 7,912