Pension and Other Postretirement Benefits - Pension Benefit Payments are Expected to be Paid (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Public Service Company of New Mexico \| Pension Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	$ 46,600
2021	45,636
2022	44,702
2023	43,595
2024	42,637
2024 - 2028	193,885
Public Service Company of New Mexico \| Other Postretirement Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	6,770
2021	6,584
2022	6,216
2023	6,017
2024	5,755
2024 - 2028	24,122
Public Service Company of New Mexico \| Executive Retirement Program
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	1,459
2021	1,424
2022	1,383
2023	1,335
2024	1,280
2024 - 2028	5,419
Texas-New Mexico Power Company \| Pension Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	5,321
2021	5,244
2022	5,111
2023	4,895
2024	4,652
2024 - 2028	20,846
Texas-New Mexico Power Company \| Other Postretirement Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	647
2021	670
2022	695
2023	709
2024	719
2024 - 2028	3,497
Texas-New Mexico Power Company \| Executive Retirement Program
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	93
2021	90
2022	86
2023	82
2024	76
2024 - 2028	$ 273

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Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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