v3.26.3
Segment Information - Schedule of Financial Information by Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Segment Reporting, Profit (Loss) [Abstract]          
Operating revenues $ 733,290 $ 647,162 $ 1,786,826 $ 1,632,374  
Administrative and general - direct 60,104 59,900 173,866 179,931  
Administrative and general - corporate allocation 0 0 0 0  
Customer related expenses 8,767 8,545 26,786 25,274  
Regulatory disallowances   (731)   (731)  
Depreciation and amortization 112,346 105,012 339,300 314,798  
Transmission and distribution costs 28,226 27,167 79,490 79,133  
Taxes other than income taxes 30,998 28,185 93,848 82,864  
Total operating expenses 462,202 444,292 1,315,425 1,284,914  
Net other income and (deductions) 348 22,532 33,635 54,660  
Interest charges (76,059) (70,149) (213,997) (205,713)  
Income taxes (benefit) 27,376 18,949 39,643 21,293  
Valencia non-controlling interest (4,440) (5,462) (12,570) (13,509)  
Subsidiary preferred stock dividends (132) (132) (396) (396)  
Net earnings (losses) available for common stock 163,429 130,710 238,430 161,209  
Total Assets 12,824,110 11,971,534 12,824,110 11,971,534 $ 12,059,285
Goodwill 278,297 278,297 278,297 278,297 $ 278,297
PNM          
Segment Reporting, Profit (Loss) [Abstract]          
Administrative and general - direct 24,990 22,764 63,963 57,233  
Administrative and general - corporate allocation 31,547 30,865 97,275 98,270  
Customer related expenses 7,903 7,792 24,261 23,054  
Regulatory disallowances   (731)   (731)  
Depreciation and amortization 67,009 61,366 196,429 181,947  
Transmission and distribution costs 17,507 18,127 50,823 49,703  
Taxes other than income taxes 15,454 14,111 48,673 42,676  
Total operating expenses 341,029 328,319 951,032 932,094  
Net other income and (deductions) (3,666) 17,334 22,511 47,139  
Interest charges (34,026) (33,805) (99,390) (95,596)  
Income taxes (benefit) 17,596 10,907 21,255 13,280  
Valencia non-controlling interest (4,440) (5,462) (12,570) (13,509)  
Subsidiary preferred stock dividends (132) (132) (396) (396)  
Net earnings (losses) available for common stock 126,939 102,429 156,823 127,736  
Total Assets 8,022,581 7,793,306 8,022,581 7,793,306  
Goodwill 51,632 51,632 51,632 51,632  
TNMP          
Segment Reporting, Profit (Loss) [Abstract]          
Administrative and general - direct (1,669) 969 (2,698) (948)  
Administrative and general - corporate allocation 13,597 12,136 41,833 39,621  
Customer related expenses 864 753 2,525 2,220  
Regulatory disallowances   0   0  
Depreciation and amortization 36,215 34,956 114,351 105,095  
Transmission and distribution costs 10,719 9,040 28,667 29,430  
Taxes other than income taxes 14,011 12,659 39,861 35,607  
Total operating expenses 118,879 112,702 357,066 334,728  
Net other income and (deductions) 4,398 5,623 11,986 9,723  
Interest charges (23,280) (24,754) (66,711) (66,018)  
Income taxes (benefit) 13,672 10,479 31,427 21,498  
Valencia non-controlling interest 0 0 0 0  
Subsidiary preferred stock dividends 0 0 0 0  
Net earnings (losses) available for common stock 54,029 41,130 124,653 84,381  
Total Assets 4,608,874 4,013,441 4,608,874 4,013,441  
Goodwill 226,665 226,665 226,665 226,665  
Corporate and Other          
Segment Reporting, Profit (Loss) [Abstract]          
Administrative and general - direct 36,783 36,167 112,601 123,646  
Administrative and general - corporate allocation (45,144) (43,001) (139,108) (137,891)  
Customer related expenses 0 0 0 0  
Regulatory disallowances   0   0  
Depreciation and amortization 9,122 8,690 28,520 27,756  
Transmission and distribution costs 0 0 0 0  
Taxes other than income taxes 1,533 1,415 5,314 4,581  
Total operating expenses 2,294 3,271 7,327 18,092  
Net other income and (deductions) (384) (425) (862) (2,202)  
Interest charges (18,753) (11,590) (47,896) (44,099)  
Income taxes (benefit) (3,892) (2,437) (13,039) (13,485)  
Valencia non-controlling interest 0 0 0 0  
Subsidiary preferred stock dividends 0 0 0 0  
Net earnings (losses) available for common stock (17,539) (12,849) (43,046) (50,908)  
Total Assets 192,655 164,787 192,655 164,787  
Goodwill 0 0 0 0  
Electric operating revenues          
Segment Reporting, Profit (Loss) [Abstract]          
Operating revenues 733,290 647,162 1,786,826 1,632,374  
Energy costs 198,506 195,042 529,137 531,846  
Electric operating revenues | PNM          
Segment Reporting, Profit (Loss) [Abstract]          
Operating revenues 527,828 463,720 1,218,955 1,135,472  
Electric operating revenues | TNMP          
Segment Reporting, Profit (Loss) [Abstract]          
Operating revenues 205,462 183,442 567,871 496,902  
Electric operating revenues | Corporate and Other          
Segment Reporting, Profit (Loss) [Abstract]          
Operating revenues 0 0 0 0  
Fuel burn          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 25,803 26,312 86,108 82,780  
Fuel burn | PNM          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 25,803 26,312 86,108 82,780  
Fuel burn | TNMP          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 0 0 0 0  
Fuel burn | Corporate and Other          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 0 0 0 0  
Purchases for resale          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 119,327 119,834 287,368 305,939  
Purchases for resale | PNM          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 119,327 119,834 287,368 305,939  
Purchases for resale | TNMP          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 0 0 0 0  
Purchases for resale | Corporate and Other          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 0 0 0 0  
Transmission by others          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 53,376 48,896 155,661 143,127  
Transmission by others | PNM          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 8,234 6,707 23,134 19,424  
Transmission by others | TNMP          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 45,142 42,189 132,527 123,703  
Transmission by others | Corporate and Other          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 0 0 0 0  
Energy production costs          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 23,255 21,172 72,998 71,799  
Energy production costs | PNM          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 23,255 21,172 72,998 71,799  
Energy production costs | TNMP          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs 0 0 0 0  
Energy production costs | Corporate and Other          
Segment Reporting, Profit (Loss) [Abstract]          
Energy costs $ 0 $ 0 $ 0 $ 0