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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, 2018 | Dec. 31, 2017
Public Service Company of New Mexico | Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | $ (34,769) | $ 27,547
Claims, contributions, and demographic experience | 431 | (1,249)
Other assumptions and experience | 279 | 0
Mortality rate | (6,966) | 0
Actuarial (gain) loss | (41,025) | 26,298
Public Service Company of New Mexico | Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | (4,076) | 3,536
Claims, contributions, and demographic experience | (3,174) | (5,845)
Assumed participation rate | (4,040) | 0
Mortality rate | (916) | 0
Medical benefits | 0 | 1,425
Dental trend assumption | 0 | (717)
Actuarial (gain) loss | (12,206) | (1,601)
Texas-New Mexico Power Company | Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | (4,278) | 3,528
Claims, contributions, and demographic experience | (301) | (517)
Other assumptions and experience | 68 | 39
Mortality rate | (705) | 0
Actuarial (gain) loss | (5,216) | 3,050
Texas-New Mexico Power Company | Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rates | (710) | 613
Claims, contributions, and demographic experience | 72 | (994)
Assumed participation rate | (1,461) | 0
Mortality rate | (114) | 0
Medical benefits | 0 | 0
Dental trend assumption | 0 | 0
Actuarial (gain) loss | $ (2,213) | $ (381)

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- Definition Defined Benefit Plan, Actuarial Gain (Loss) resulting from changes in demographics and other trends + 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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