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

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Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transaction [Line Items]
Ownership percentage	50.00%		50.00%
Services billings: \| PNMR to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	$ 26,150	$ 24,521	$ 52,375	$ 46,644
Services billings: \| PNMR to TNMP
Related Party Transaction [Line Items]
Amount of related party transaction	10,135	9,703	20,500	18,430
Services billings: \| PNM to TNMP
Related Party Transaction [Line Items]
Amount of related party transaction	94	113	212	189
Services billings: \| TNMP to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	12	35	24	70
Services billings: \| PNMR to NMRD
Related Party Transaction [Line Items]
Amount of related party transaction	55	49	110	125
Renewable energy purchases: \| PNM from NMRD
Related Party Transaction [Line Items]
Amount of related party transaction	3,504	2,404	6,089	3,923
Interconnection billings: \| PNM from NMRD
Related Party Transaction [Line Items]
Amount of related party transaction	0	130	0	350
Interconnection billings: \| PNM to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	0	0	0	0
Interconnection billings: \| NMRD to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	0	0	1,276	0
Interest billings: \| PNMR to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	0	6	0	6
Interest billings: \| PNMR to TNMP
Related Party Transaction [Line Items]
Amount of related party transaction	0	1	0	2
Interest billings: \| PNM to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	36	77	72	158
Income tax sharing payments: \| PNMR to PNM
Related Party Transaction [Line Items]
Amount of related party transaction	0	0	0	0
Income tax sharing payments: \| TNMP to PNMR
Related Party Transaction [Line Items]
Amount of related party transaction	$ 0	$ 0	$ 0	$ 0