Asset Retirement Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Asset Retirement Obligations [Line Items]
ARO liabilities related to nuclear decommissioning	62.00%
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 183,421	$ 181,962	$ 158,674
Liabilities incurred	1,781	0	0
Liabilities settled	(142)	(1,444)	(987)
Accretion expense	9,308	11,310	12,635
Revisions to estimated cash flows	39,778	(8,407)	11,640
Ending balance	234,146	183,421	181,962
Four Corners
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Revisions to estimated cash flows	800
Palo Verde Nuclear Generating Station
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Revisions to estimated cash flows	9,200
Public Service Company of New Mexico
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	182,718	181,081	157,814
Liabilities incurred	1,781	0	0
Liabilities settled	(142)	(1,192)	(935)
Accretion expense	9,248	11,236	12,562
Revisions to estimated cash flows	39,778	(8,407)	11,640
Ending balance	233,383	182,718	181,081
Texas-New Mexico Power Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	703	881	860
Liabilities incurred	0	0	0
Liabilities settled	0	(252)	(52)
Accretion expense	60	74	73
Revisions to estimated cash flows	0	0	0
Ending balance	$ 763	$ 703	$ 881

Asset Retirement Obligation, Liabilities Related to Nuclear Decommissioning

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- Definition

Asset Retirement Obligations [Line Items]

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848

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Amount of asset retirement obligations incurred during the period.

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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 35
-Paragraph 8
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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