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Financing - Financing Activities (Details) |  |  |  |  |  |  |  | 3 Months Ended |  |
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May 04, 2023 USD ($) derivative | Mar. 15, 2023 USD ($) derivative | Nov. 10, 2022 USD ($) | Oct. 31, 2022 USD ($) derivative | Sep. 30, 2022 USD ($) derivative | May 20, 2022 USD ($) | May 02, 2022 USD ($) derivative | Mar. 31, 2023 USD ($) $ / shares shares | Apr. 28, 2023 USD ($) numberOfAMIMeter bond | Apr. 27, 2022 USD ($) bond
Bank Of America, N.A. |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Forward sale agreement (in shares) | shares |  |  |  |  |  |  |  | 504,452 |  |
Forward sale agreement (in dollars per share) | $ / shares |  |  |  |  |  |  |  | $ 48.49 |  |
Wells Fargo Bank, N.A. |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Forward sale agreement (in shares) | shares |  |  |  |  |  |  |  | 528,082 |  |
Forward sale agreement (in dollars per share) | $ / shares |  |  |  |  |  |  |  | $ 48.30 |  |
At-The-Market |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Distribution agreement |  |  | $ 200,000,000 |  |  |  |  |  |  |
Variable Rate Debt | Interest rate contract | Cash Flow Hedge |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Number of instruments held | derivative |  |  |  | 2 | 2 |  | 2 |  |  |
Term of loan |  |  |  | 14 months | 15 months | 19 months | 20 months |  |  |
Derivative asset, notional amount |  |  |  | $ 200,000,000 | $ 200,000,000 |  |  |  |  |
Derivative, notional amount |  |  |  |  |  | $ 100,000,000 |  |  |  |
Fixed interest rate |  |  |  |  |  | 2.52% | 2.65% |  |  |
Derivative instruments in hedges, fair value |  |  |  |  |  |  |  | $ 8,700,000 |  |
Variable Rate Debt | Interest rate contract | Cash Flow Hedge | Other Current Assets |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative instruments in hedges, fair value |  |  |  |  |  |  |  | 8,400,000 |  |
Variable Rate Debt | Interest rate contract | Cash Flow Hedge | Other Deferred Costs Net Including Deferred Finance Costs |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative instruments in hedges, fair value |  |  |  |  |  |  |  | $ 300,000 |  |
Variable Rate Debt | Interest rate contract | Cash Flow Hedge | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Number of instruments held | derivative | 3 |  |  |  |  |  |  |  |  |
Derivative asset, notional amount | $ 300,000,000 |  |  |  |  |  |  |  |  |
Variable Rate Debt, Tranche 1 | Interest rate contract | Cash Flow Hedge |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of loan |  | 6 months |  |  |  |  |  |  |  |
Derivative asset, notional amount |  | $ 150,000,000 |  | $ 100,000,000 | $ 100,000,000 |  | $ 150,000,000 |  |  |
Fixed interest rate |  | 4.57% |  | 4.66% |  |  |  |  |  |
Variable interest rate |  |  |  |  | 4.17% |  |  |  |  |
Variable Rate Debt, Tranche 1 | Interest rate contract | Cash Flow Hedge | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of loan | 12 months |  |  |  |  |  |  |  |  |
Derivative asset, notional amount | $ 100,000,000 |  |  |  |  |  |  |  |  |
Fixed interest rate | 3.32% |  |  |  |  |  |  |  |  |
Variable Rate Debt, Tranche 2 | Interest rate contract | Cash Flow Hedge |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of loan |  | 12 months |  |  |  |  |  |  |  |
Derivative asset, notional amount |  | $ 150,000,000 |  | $ 100,000,000 | $ 100,000,000 |  | $ 200,000,000 |  |  |
Fixed interest rate |  | 3.57% |  | 4.65% |  |  |  |  |  |
Variable interest rate |  |  |  |  | 4.18% |  |  |  |  |
Variable Rate Debt, Tranche 2 | Interest rate contract | Cash Flow Hedge | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of loan | 12 months |  |  |  |  |  |  |  |  |
Derivative asset, notional amount | $ 100,000,000 |  |  |  |  |  |  |  |  |
Fixed interest rate | 3.32% |  |  |  |  |  |  |  |  |
Variable Rate Debt, Tranche 3 | Interest rate contract | Cash Flow Hedge |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of loan |  | 12 months |  |  |  |  |  |  |  |
Derivative asset, notional amount |  | $ 150,000,000 |  |  |  |  |  |  |  |
Fixed interest rate |  | 3.62% |  |  |  |  |  |  |  |
Variable Rate Debt, Tranche 3 | Interest rate contract | Cash Flow Hedge | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of loan | 12 months |  |  |  |  |  |  |  |  |
Derivative asset, notional amount | $ 100,000,000 |  |  |  |  |  |  |  |  |
Fixed interest rate | 3.38% |  |  |  |  |  |  |  |  |
Variable Rate Debt, Tranche 2 And 3 | Interest rate contract | Cash Flow Hedge |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Number of instruments held | derivative |  | 2 |  |  |  |  |  |  |  |
Derivative asset, notional amount |  | $ 300,000,000 |  |  |  |  |  |  |  |
PNM |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Maturity term over which financings require regulator approval (more than) |  |  |  |  |  |  |  | 18 months |  |
Line of credit |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Ratio of debt to capital (less than or equal to) |  |  |  |  |  |  |  | 70.00% |  |
Line of credit | PNM and TNMP |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Ratio of debt to capital (less than or equal to) |  |  |  |  |  |  |  | 65.00% |  |
Unsecured Debt | PNM | PNM 2023 Note Purchase Agreement | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  | $ 200,000,000 |
Number of debt issuances | numberOfAMIMeter |  |  |  |  |  |  |  |  | 2 |
Unsecured Debt | PNM | PNM 2023 SUNs At 5.1%, Due April 28, 2035 | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  | $ 150,000,000 |
Stated interest rate |  |  |  |  |  |  |  |  | 5.51% |
Unsecured Debt | PNM | PNM 2023 SUNs At 5.92%, Due April 28, 2053 | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  | $ 50,000,000 |
Stated interest rate |  |  |  |  |  |  |  |  | 5.92% |
Mortgage Bonds | PNM | TNMP 2023 Bond Purchase Agreement | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, series of bond issuance | bond |  |  |  |  |  |  |  |  | 2 |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2023 Bond Purchase Agreement | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  | $ 185,000,000 |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2023 Bond Purchase Agreement At 5.01%, Due April 28, 2033 | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  | $ 130.0 |
Stated interest rate |  |  |  |  |  |  |  |  | 5.01% |
Mortgage Bonds | Texas-New Mexico Power Company | TNMP 2023 Bond Purchase Agreement At 5.47%, Due July 28, 2053 | Subsequent event |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  | $ 55.0 |
Stated interest rate |  |  |  |  |  |  |  |  | 5.47% |
Bonds | PNMR 2021 Delayed-Draw Term Loan |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 5.84% |  |
Bonds | PNM | PNM 2021 75 Million Term Loan |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Variable interest rate |  |  |  |  |  |  |  | 5.60% |  |
Bonds | Texas-New Mexico Power Company | TNMP 2022 Bond Purchase Agreement |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 160,000,000
Debt instrument, series of bond issuance | bond |  |  |  |  |  |  |  |  |  | 2
Bonds | Texas-New Mexico Power Company | TNMP 2022 Bond Purchase Agreement at 4.13% Due May 12, 2022 |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 65,000,000
Stated interest rate |  |  |  |  |  |  |  |  |  | 4.13%
Bonds | Texas-New Mexico Power Company | TNMP 2022 Bond Purchase Agreement at 3.81% Due July 28, 2032 |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  |  |  |  |  |  |  | $ 95,000,000
Stated interest rate |  |  |  |  |  |  |  |  |  | 3.81%

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