Pension and Other Postretirement Benefits - Pension Benefit Payments are Expected to be Paid (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Public Service Company of New Mexico \| Pension Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	$ 46,125
2020	45,595
2021	44,804
2022	44,000
2023	43,066
2024 - 2028	199,157
Public Service Company of New Mexico \| Other Postretirement Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	7,365
2020	7,309
2021	7,029
2022	6,653
2023	6,351
2024 - 2028	26,678
Public Service Company of New Mexico \| Executive Retirement Program
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	1,627
2020	1,463
2021	1,427
2022	1,385
2023	1,337
2024 - 2028	5,792
Texas-New Mexico Power Company \| Pension Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	5,137
2020	5,065
2021	5,005
2022	4,886
2023	4,667
2024 - 2028	21,075
Texas-New Mexico Power Company \| Other Postretirement Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	629
2020	653
2021	674
2022	699
2023	714
2024 - 2028	3,558
Texas-New Mexico Power Company \| Executive Retirement Program
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	141
2020	91
2021	88
2022	84
2023	79
2024 - 2028	$ 301

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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 next 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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