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Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Apr. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 01, 2018
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill	$ 278,297		$ 278,297	$ 278,297
Public Service Company of New Mexico
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill	51,632		51,632		$ 51,600
Percentage of fair value in excess of carrying amount					19.00%
Texas-New Mexico Power Company
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill	$ 226,665	$ 226,700	$ 226,665		$ 226,700
Percentage of fair value in excess of carrying amount		38.00%			32.00%

X

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975

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-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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+ References

No definition available.

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- Definition

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+ References

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