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Pension and Other Postretirement Benefits - Schedule of Assumed Health Care Cost Trend Rates for the PNM OPEB Plan (Details) - PNM - Other Postretirement Benefits | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract] |  |
Health care cost trend rate assumed for next year | 6.50% | 6.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) | 4.75% | 4.75%
Year that the rate reaches the ultimate trend rate | 2033 | 2029

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- Definition Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Ultimate trend rate for health care cost for defined benefit postretirement plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Year ultimate health care cost trend rate is expected to be reached, in YYYY format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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