Pension and Other Postretirement Benefits - Pension Benefit Payments are Expected to be Paid (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Public Service Company of New Mexico \| Pension Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2018	$ 49,221
2019	48,639
2020	47,069
2021	45,246
2022	44,232
2023 - 2027	201,389
Public Service Company of New Mexico \| Other Postretirement Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2018	7,829
2019	7,730
2020	7,605
2021	7,442
2022	7,132
2023 - 2027	31,250
Public Service Company of New Mexico \| Executive Retirement Program
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2018	1,501
2019	1,473
2020	1,441
2021	1,405
2022	1,363
2023 - 2027	6,014
Texas-New Mexico Power Company \| Pension Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2018	5,929
2019	5,215
2020	5,108
2021	5,373
2022	4,856
2023 - 2027	22,085
Texas-New Mexico Power Company \| Other Postretirement Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2018	708
2019	725
2020	748
2021	774
2022	795
2023 - 2027	4,126
Texas-New Mexico Power Company \| Executive Retirement Program
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2018	93
2019	91
2020	89
2021	85
2022	81
2023 - 2027	$ 324

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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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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