Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 2,244,926	$ 2,222,929	$ 2,108,474
Total Other Comprehensive Income	3,208	5,888	7,247
Ending Balance	2,399,051	2,244,926	2,222,929
PNM
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1,960,324	2,015,264	1,863,752
Total Other Comprehensive Income	7,830	(2,399)	6,575
Ending Balance	2,000,775	1,960,324	2,015,264
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(66,048)	(71,936)	(79,183)
Amounts reclassified from AOCI (pre-tax)	6,864	2,101	(2,320)
Income tax impact of amounts reclassified	(1,743)	(533)	589
Other OCI changes (pre-tax)	(2,565)	5,792	12,034
Income tax impact of other OCI changes	652	(1,472)	(3,056)
Total Other Comprehensive Income	3,208	5,888	7,247
Ending Balance	(62,840)	(66,048)	(71,936)
Total | PNM
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(74,335)	(71,936)	(78,511)
Amounts reclassified from AOCI (pre-tax)	(2,423)	3,277	(1,417)
Income tax impact of amounts reclassified	616	(832)	360
Other OCI changes (pre-tax)	12,918	(6,493)	10,230
Income tax impact of other OCI changes	(3,281)	1,649	(2,598)
Total Other Comprehensive Income	7,830	(2,399)	6,575
Ending Balance	(66,505)	(74,335)	(71,936)
Unrealized Gains on Available-for-Sale Securities | PNM
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	7,422	11,715	20,403
Amounts reclassified from AOCI (pre-tax)	(7,199)	(3,827)	(9,765)
Income tax impact of amounts reclassified	1,828	972	2,480
Other OCI changes (pre-tax)	11,529	(1,928)	(1,881)
Income tax impact of other OCI changes	(2,928)	490	478
Total Other Comprehensive Income	3,230	(4,293)	(8,688)
Ending Balance	10,652	7,422	11,715
Pension Liability Adjustment | PNM
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(81,757)	(83,651)	(98,914)
Amounts reclassified from AOCI (pre-tax)	4,776	7,104	8,348
Income tax impact of amounts reclassified	(1,212)	(1,804)	(2,120)
Other OCI changes (pre-tax)	1,389	(4,565)	12,111
Income tax impact of other OCI changes	(353)	1,159	(3,076)
Total Other Comprehensive Income	4,600	1,894	15,263
Ending Balance	(77,157)	(81,757)	(83,651)
Fair Value Adjustment for Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	8,287	0	(672)
Amounts reclassified from AOCI (pre-tax)	9,287	(1,176)	(903)
Income tax impact of amounts reclassified	(2,359)	299	229
Other OCI changes (pre-tax)	(15,483)	12,285	1,804
Income tax impact of other OCI changes	3,933	(3,121)	(458)
Total Other Comprehensive Income	(4,622)	8,287	672
Ending Balance	$ 3,665	$ 8,287	$ 0