Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Related Party Transaction [Line Items]
Ownership percentage	50.00%
Services billings: \| PNMR to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	$ 26,225	$ 22,123
Services billings: \| PNMR to TNMP
Related Party Transaction [Line Items]
Amount of related party transaction	10,365	8,727
Services billings: \| PNM to TNMP
Related Party Transaction [Line Items]
Amount of related party transaction	118	76
Services billings: \| TNMP to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	12	35
Services billings: \| PNMR to NMRD
Related Party Transaction [Line Items]
Amount of related party transaction	55	76
Renewable energy purchases: \| PNM from NMRD
Related Party Transaction [Line Items]
Amount of related party transaction	2,585	1,519
Interconnection billings: \| PNM from NMRD
Related Party Transaction [Line Items]
Amount of related party transaction	0	220
Interconnection billings: \| PNM to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	0	0
Interconnection billings: \| NMRD to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	1,276	0
Interest billings: \| PNMR to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	0	0
Interest billings: \| PNMR to TNMP
Related Party Transaction [Line Items]
Amount of related party transaction	0	1
Interest billings: \| PNM to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	36	81
Income tax sharing payments: \| PNMR to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	0	0
Income tax sharing payments: \| TNMP to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	$ 0	$ 0

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

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Balance Type:	na
Period Type:	instant

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Details

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