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Quarterly Operating Results (Unaudited) (Details) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2018 USD ($) $ / shares MW | Sep. 30, 2018 USD ($) $ / shares | Jun. 30, 2018 USD ($) $ / shares | Mar. 31, 2018 USD ($) $ / shares | Dec. 31, 2017 USD ($) $ / shares | Sep. 30, 2017 USD ($) $ / shares | Jun. 30, 2017 USD ($) $ / shares | Mar. 31, 2017 USD ($) $ / shares | Dec. 31, 2018 USD ($) $ / shares MW | Dec. 31, 2017 USD ($) $ / shares | Dec. 31, 2016 USD ($) $ / shares | Dec. 16, 2015 MW | Jul. 31, 2015 MW
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  | $ 1,436,613 | $ 1,445,003 | $ 1,362,951 |  |
Operating income | $ (17,404) | $ 127,990 | $ 79,329 | $ 46,132 | $ 22,936 | $ 142,484 | $ 85,105 | $ 55,960 | 236,047 | 315,039 | 284,725 |  |
Net earnings (loss) | (51,539) | 91,573 | 42,449 | 18,799 | (50,585) | 78,327 | 41,231 | 26,446 | $ 101,282 | $ 95,419 | $ 131,896 |  |
Net Earnings Attributable to PNMR | $ (55,077) | $ 87,521 | $ 38,208 | $ 14,990 | $ (54,282) | $ 73,739 | $ 37,555 | $ 22,862 |  |  |  |  |
Net Earnings Attributable to PNMR per Common Share: |  |  |  |  |  |  |  |  |  |  |  |  |
Basic (in dollars per share) | $ / shares | $ (0.70) | $ 1.10 | $ 0.48 | $ 0.19 | $ (0.68) | $ 0.92 | $ 0.47 | $ 0.29 | $ 1.07 | $ 1.00 | $ 1.47 |  |
Diluted (in dollars per share) | $ / shares | $ (0.69) | $ 1.09 | $ 0.48 | $ 0.19 | $ (0.68) | $ 0.92 | $ 0.47 | $ 0.29 | $ 1.07 | $ 1.00 | $ 1.46 |  |
Federal income tax rate change |  |  |  |  |  |  |  |  | $ 2,914 | $ 57,461 | $ 0 |  |
Public Service Company of New Mexico |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  | 1,091,965 | 1,104,230 | 1,035,913 |  |
Operating income | $ (38,654) | $ 102,516 | $ 52,879 | $ 28,292 | $ 1,778 | $ 113,252 | $ 59,164 | $ 38,331 | 145,033 | 221,079 | 194,830 |  |
Net earnings (loss) | (53,400) | 81,428 | 30,781 | 11,514 | (28,456) | 65,283 | 30,476 | 20,110 | 70,323 | 87,413 | 91,938 |  |
Net Earnings Attributable to PNMR | (56,806) | 77,508 | 26,672 | 7,837 | (32,021) | 60,827 | 26,932 | 16,658 | 55,211 | 72,396 | 77,419 |  |
Net Earnings Attributable to PNMR per Common Share: |  |  |  |  |  |  |  |  |  |  |  |  |
Federal income tax rate change |  |  |  |  |  |  |  |  | (683) | 29,606 | 0 |  |
Texas-New Mexico Power Company |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues |  |  |  |  |  |  |  |  | 344,648 | 340,773 | 327,038 |  |
Operating income | 23,312 | 27,824 | 26,829 | 18,532 | 19,879 | 29,474 | 26,286 | 17,965 | 96,497 | 93,604 | 91,641 |  |
Net Earnings Attributable to PNMR | 10,711 | 16,100 | 15,367 | 9,413 | 1,024 | 14,727 | 12,204 | 7,604 | 51,591 | 35,559 | 41,672 |  |
Net Earnings Attributable to PNMR per Common Share: |  |  |  |  |  |  |  |  |  |  |  |  |
Federal income tax rate change |  |  |  |  |  |  |  |  | 0 | 7,865 | 0 |  |
NMPRC |  |  |  |  |  |  |  |  |  |  |  |  |
Net Earnings Attributable to PNMR per Common Share: |  |  |  |  |  |  |  |  |  |  |  |  |
Pre-tax regulatory disallowance |  |  |  |  | 27,900 |  |  |  |  | 27,900 |  |  |
Electricity |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues | 343,756 | 422,666 | 352,313 | 317,878 | 332,605 | 419,900 | 362,320 | 330,178 | 1,436,613 | $ 1,445,003 | $ 1,362,951 |  |
Electricity | Public Service Company of New Mexico |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues | 259,848 | 331,374 | 264,511 | 236,232 | 249,321 | 327,254 | 276,097 | 251,558 |  |  |  |  |
Electricity | Texas-New Mexico Power Company |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Revenues | $ 83,908 | $ 91,292 | $ 87,802 | $ 81,646 | $ 83,284 | $ 92,646 | $ 86,223 | $ 78,620 |  |  |  |  |
Clean Air Act, SNCR | San Juan Generating Station Unit 4 | Public Service Company of New Mexico |  |  |  |  |  |  |  |  |  |  |  |  |
Net Earnings Attributable to PNMR per Common Share: |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory disallowance and restructuring costs |  |  |  |  |  |  |  |  | $ 63,300 |  |  |  |
Additional ownership to be obtained (in megawatts) | MW | 65 |  |  |  |  |  |  |  | 65 |  |  | 65 | 132
Potential acquisition of ownership (in megawatts) | MW | 65 |  |  |  |  |  |  |  | 65 |  |  |  |
Clean Air Act, SNCR Hearing Examiner Recommended Denial | San Juan Generating Station Unit 4 | Public Service Company of New Mexico |  |  |  |  |  |  |  |  |  |  |  |  |
Net Earnings Attributable to PNMR per Common Share: |  |  |  |  |  |  |  |  |  |  |  |  |
Additional ownership to be obtained (in megawatts) | MW | 132 |  |  |  |  |  |  |  | 132 |  |  | 132 |

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