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Pension and Other Postretirement Benefits - Actuarial (Gain) Loss Results (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
PNM | Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | $ 8,806 | $ (111,478)
Claims, contributions, and demographic experience | (1,777) | (7,074)
Mortality rate | (2,739) | 0
Other assumptions and experience | 0 | 0
Actuarial (gain) loss | 4,290 | (118,552)
PNM | Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | 868 | (11,876)
Claims, contributions, and demographic experience | (2,171) | (2,985)
Assumed participation rate | 0 | 0
Mortality rate | (305) | 0
Dental trend assumption | 0 | 32
Actuarial (gain) loss | (1,608) | (14,829)
TNMP | Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | 969 | (11,697)
Claims, contributions, and demographic experience | 538 | (742)
Mortality rate | (239) | 0
Other assumptions and experience | (7) | 728
Actuarial (gain) loss | 1,261 | (11,711)
TNMP | Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | 174 | (2,469)
Claims, contributions, and demographic experience | (423) | (319)
Assumed participation rate | 0 | 0
Mortality rate | (33) | 0
Dental trend assumption | 0 | 0
Actuarial (gain) loss | $ (282) | $ (2,788)

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- Definition Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Dental Trend Assumption + References No definition available. + Details
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- Definition Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Participation Rate + References No definition available. + Details
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- Definition Defined Benefit Plan, Benefit Obligation, Increase (Decrease) In Discount Rates + References No definition available. + Details
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- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a)(4) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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