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Pension and Other Postretirement Benefits - Actuarial (Gain) Loss Results (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019
Public Service Company of New Mexico | Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | $ 44,960 | $ 66,108
Claims, contributions, and demographic experience | 2,607 | (732)
Mortality rate | 0 | (4,225)
Other assumptions and experience | 0 | 0
Actuarial (gain) loss | 47,567 | 61,151
Public Service Company of New Mexico | Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | 4,959 | 7,236
Claims, contributions, and demographic experience | (1,698) | (4,022)
Mortality rate | 0 | (627)
Assumed participation rate | 0 | 0
Actuarial (gain) loss | 3,261 | 2,587
Texas-New Mexico Power Company | Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | 4,756 | 8,006
Claims, contributions, and demographic experience | (54) | 394
Mortality rate | 0 | (296)
Other assumptions and experience | (243) | (215)
Actuarial (gain) loss | 4,459 | 7,889
Texas-New Mexico Power Company | Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | 1,008 | 1,375
Claims, contributions, and demographic experience | (261) | (311)
Mortality rate | 0 | (60)
Assumed participation rate | 0 | 0
Actuarial (gain) loss | $ 747 | $ 1,004

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- Definition Defined Benefit Plan, Actuarial Gain (Loss) resulting from changes in other assumptions and experience + 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 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 -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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