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Summary of the Business and Significant Accounting Policies - Schedule of Average Straight-Line Rates and Depreciation on Electric, Common, Intangible, and General Plant (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
PNM |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Depreciation | $ 188,035 | $ 158,956 | $ 163,162
TNMP |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Average straight-line rate (as a percent) | 3.74% | 3.77% | 3.72%
Depreciation | $ 124,976 | $ 110,675 | $ 96,131
Electric plant | PNM |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Average straight-line rate (as a percent) | 2.87% | 2.67% | 2.55%
Common, intangible, and general plant | PNM |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Average straight-line rate (as a percent) | 14.06% | 7.64% | 7.83%

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- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-1 + Details
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