Schedule of Short-term Debt Schedule of Short-Term Debt [Table Text Block] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets The Bank of Nova Scotia The Bank of Nova Scotia [Member] The Bank of Nova Scotia Weighted average discount rate: Leases, Weighted Average Discount Rate [Abstract] Leases, Weighted Average Discount Rate [Abstract] Award Timing Predetermined Award Timing Predetermined [Flag] NM Capital NM Capital [Member] NM Capital [Member] Entity File Number Entity File Number Paid-in Capital Additional Paid-in Capital [Member] Reclassification adjustment for (gains) included in net earnings, net of income tax expense of $38 and $35 Reclassification adjustment for (gains) included in net earnings, net of income tax expense of $38 and $35 Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Tabular List, Table Tabular List [Table Text Block] New Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] PNM 2025 Bond At Six Point One Three, Due June Twenty Thirty Seven PNM April 2025 SUNSs At Six Point One Three, Due June Twenty Thirty Seven [Member] PNM April 2025 SUNSs At Six Point One Three, Due June Twenty Thirty Seven Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Schedule of Carrying Amount and Fair Value of Items Not Recorded at Fair Value Fair Value, by Balance Sheet Grouping [Table Text Block] Goodwill [Line Items] Goodwill [Line Items] Measurement Basis [Axis] Measurement Basis [Axis] Other (deductions) Other Expenses Adjustment to Compensation: Adjustment to Compensation [Axis] Related Party Transactions Related Party Transactions Disclosure [Text Block] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Catastrophic Event [Axis] Catastrophic Event [Axis] Electric Operating Revenues Revenue from Contract with Customer [Text Block] Pollution Control Revenue Bonds Pollution Control Revenue Bonds [Member] Pollution Control Revenue Bonds Accumulated depreciation Finance Lease, Right-Of-Use Asset, Accumulated Depreciation Finance Lease, Right-Of-Use Asset, Accumulated Depreciation Fair Value of Derivative and Other Financial Instruments Derivatives and Fair Value [Text Block] Number of regulated utilities Number Of Regulated Utilities Number Of Regulated Utilities Adjustment to Compensation, Amount Adjustment to Compensation Amount Pension Plan Pension Plan [Member] Cumulative preferred stock of subsidiary, stated value (in dollars per share) Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Par Or Stated Value Per Share Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Par Or Stated Value Per Share Principles of Consolidation Consolidation, Policy [Policy Text Block] Stock based compensation expense Share-Based Payment Arrangement, Noncash Expense Merger Agreement Merger Agreement [Member] Merger Agreement Annual funding post-term reclamation trust, year one Public Utilities, Annual Funding Post-Term Reclamation Trust, Year One Public Utilities, Annual Funding Post-Term Reclamation Trust, Year One TNMP February 2025 Bond TNMP February 2025 Bond [Member] TNMP February 2025 Bond Employee Stock Option Share-Based Payment Arrangement, Option [Member] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Dividends declared on common stock Dividends declared on common stock Dividends, Common Stock, Cash Retained earnings Beginning balance Ending balance Equity, Attributable to Parent Schedule of Available-for-sale Securities [Table] Debt Securities, Available-for-Sale [Table] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fuel burn Electricity, Fuel Burn [Member] Electricity, Fuel Burn ETBC 1 Senior Secured Energy Transition Bonds, Series A [Member] Senior Secured Energy Transition Bonds, Series A Other Comprehensive Income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Insider Trading Policies and Procedures [Line Items] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Accounts receivable and unbilled revenues Increase Decrease In Accounts Receivable And Unbilled Revenues The net change during the period in the amount due from customers for the credit sale of goods and services; includes accounts receivable billed and unbilled. Leases, Operating [Line Items] Leases, Operating [Line Items] [Line Items] for Leases, Operating [Table] Transmission interconnection and security deposit arrangements Proceeds From Transmission Interconnection And Security Deposit Arrangements Proceeds From Transmission Interconnection And Security Deposit Arrangements Other current liabilities Increase (Decrease) in Other Current Liabilities Recurring Fair Value, Recurring [Member] Weighted Average Interest Rate Line of Credit Facility, Interest Rate at Period End LIABILITIES AND STOCKHOLDER’S EQUITY Liabilities and Equity [Abstract] Capital projects Sales And Use Tax Refund, Applied To Capital Projects Sales And Use Tax Refund, Applied To Capital Projects Cover page. Cover [Abstract] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Maximum Maximum [Member] TXNM and PNM TXNM and PNM [Member] TXNM and PNM Mine Reclamation Trust Mine Reclamation Trust [Member] Mine Reclamation Trust [Member] Maximum number of shares awarded in year one (in shares) Share-Based Compensation Arrangement By Share-Based Payment Award, Maximum Number Of Shares Awarded, In Year One Share-Based Compensation Arrangement By Share-Based Payment Award, Maximum Number Of Shares Awarded, In Year One (Earnings) Attributable to Valencia Non-controlling Interest Valencia non-controlling interest Earnings attributable to non-controlling interest Net Income (Loss) Attributable to Noncontrolling Interest Collateral amount Debt Instrument, Collateral Amount Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Annual funding post-term reclamation trust Public Utilities, Annual Funding Post-Term Reclamation Trust Public Utilities, Annual Funding Post-Term Reclamation Trust Restricted Stock Restricted Stock [Member] TNMP Revolving Credit Facility TNMP Revolving Credit Facility [Member] TNMP Revolving Credit Facility [Member] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Variable Interest Entities [Abstract] Variable Interest Entities [Abstract] Variable Interest Entities [Abstract] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Estimated cost of the project is expected to be reviewed in a future rate Public Utilities, Estimated Cost Of The Project Is Expected In Future Rate Sites Public Utilities, Estimated Cost Of The Project Is Expected In Future Rate Sites Industry Wide Retrospective Assessment Program Industry Wide Retrospective Assessment Program [Member] Industry Wide Retrospective Assessment Program [Member] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Cash Flow, Lessee [Line Items] Cash Flow, Lessee [Line Items] [Line Items] for Cash Flow, Lessee [Table] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Number of monitoring wells containing free-phase hydrocarbon products Number Of Monitoring Wells Containing Free-Phase Hydrocarbon Products Number Of Monitoring Wells Containing Free-Phase Hydrocarbon Products Maximum annual premium per incident Public Utilities, Maximum Annual Premium Per Incident Public Utilities, Maximum Annual Premium Per Incident Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Earnings (Losses) before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Related Party Transaction, By Transaction Type [Axis] Related Party Transaction, By Transaction Type [Axis] Related Party Transaction, By Transaction Type [Axis] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] TXNM Revolving Credit Facility TXNM Revolving Credit Facility [Member] TXNM Revolving Credit Facility Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Comprehensive (Income) Attributable to Valencia Non-controlling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Settlement price (in dollars per share) Forward Contract Indexed to Equity, Settlement, Share, Fair Value Per Share Other receivables Receivables Other Receivables Operating lease liabilities Current portion of operating lease liabilities Operating Lease, Liability, Current Interest on lease liabilities Finance Lease, Interest Expense Other current liabilities Finance Lease, Liability, Current, Other Finance Lease, Liability, Current, Other Document Fiscal Period Focus Document Fiscal Period Focus Award Timing Method Award Timing Method [Text Block] Requested on ROE, percent TNMP Rate Base Review, Requested On ROE, Percent TNMP Rate Base Review, Requested On ROE, Percent Basic (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Jointly-Owned Generating Facilities [Axis] Jointly-Owned Generating Facilities [Axis] Jointly-Owned Generating Facilities [Axis] Award Type [Axis] Award Type [Axis] Utility Plant [Domain] Utility Plant [Domain] Trading Symbol Trading Symbol 2030 Lessee, Operating Lease, Liability, to be Paid, Year Four Number of economic development projects Public Utilities, Number Of Economic Development Projects Public Utilities, Number Of Economic Development Projects Interest billings: Interest Charges [Member] Interest Charges [Member] Entity Address, City or Town Entity Address, City or Town Development fund payment period Public Utilities, Economic Development Fund, Period Public Utilities, Economic Development Fund, Period Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Plant in service and plant held for future use Plant in service and plant held for future use Public Utilities, Property, Plant and Equipment, Plant in Service Financing leases Finance Lease, Weighted Average Discount Rate, Percent Forward Contract Indexed to Issuer's Equity [Table] Forward Contract Indexed to Issuer's Equity [Table] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Maximum potential assessment per incident Public Utilities, Maximum Potential Assessment Per Incident Public Utilities, Maximum Potential Assessment Per Incident Regulatory Agency [Axis] Regulatory Agency [Axis] Entity Emerging Growth Company Entity Emerging Growth Company Financing leases Finance Lease, Weighted Average Remaining Lease Term Amounts recognized for right to reclaim cash Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Revolving credit facilities repayments Repayments of Lines of Credit Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Non-utility property, net Property, Plant and Equipment, Other, Net Less: Imputed interest Finance Lease, Liability, Undiscounted Excess Amount Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Other receivables, allowance for credit loss, period increase Other Receivables, Allowance For Credit Loss, Period Increase (Decrease) Other Receivables, Allowance For Credit Loss, Period Increase (Decrease) Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Annual Revenue Collection Public Utilities, Revenue From Proposed Collection Public Utilities, Revenue From Proposed Collection Purchases for resale Electricity, Purchased [Member] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Prepaid and other current assets Prepaid Expense and Other Assets, Current Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income Taxes (Benefits) Income Taxes Income taxes (benefit) Income Tax Expense (Benefit) Weighted average remaining lease term (years): Weighted Average Remaining Lease Term [Abstract] Weighted Average Remaining Lease Term [Abstract] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] NMPRC NMPRC [Member] NMPRC [Member] Schedule of Leases, Supplemental Cash Flows Schedule Of Leases, Supplemental Cash Flows [Table Text Block] Schedule Of Leases, Supplemental Cash Flows [Table Text Block] Merger agreement period extension Business Combination, Merger Agreement Period Extension Business Combination, Merger Agreement Period Extension Other current assets Increase (Decrease) in Other Current Assets Bonds Notes Payable, Other Payables [Member] Operating lease, right-of-use asset, amortization expense Operating Lease, Right-of-Use Asset, Periodic Reduction Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Portfolio One Portfolio One [Member] Portfolio One Disbursements by employer Defined Benefit Plan, Plan Assets, Disbursements By Employer Defined Benefit Plan, Plan Assets, Disbursements By Employer All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Subsidiary preferred stock dividends Preferred Stock Dividends, Income Statement Impact Outstanding at beginning of period (in shares) Outstanding at end of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Transmission and distribution costs Transmission And Distribution Costs Costs incurred for transmission and distribution of electricity Net cash flows from operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Debt instrument, term Debt Instrument, Term Proceeds from sales Proceeds from Sale of Debt Securities, Available-for-Sale Customer reclamation funding cost Customer Reclamation Funding Cost, Maximum Customer Reclamation Funding Cost, Maximum Number of sites Public Utilities, Number Of Sites Number Of Sites Subsequent Event Subsequent Event [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Purchase Commitment, Excluding Long-term Commitment [Axis] Purchase Commitment, Excluding Long-Term Commitment [Axis] Surety bond Loss Contingency, Surety Bond Loss Contingency, Surety Bond 2030 Finance Lease, Liability, to be Paid, Year Four Average Number of Common Shares: Weighted Average Number of Shares Outstanding, Basic [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Components [Axis] Convertible Debt Convertible Debt [Member] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Reclassification adjustment for (gains) losses included in net earnings, income tax expense (benefit) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Number of reportable segments Number of Reportable Segments Related Party Transaction, by Transaction Type [Domain] Related Party Transaction, by Transaction Type [Domain] Related Party Transaction, by Transaction Type [Domain] Energy Storage Facilities Energy Storage Facilities [Member] Energy Storage Facilities Vesting rate Share-based Compensation Arrangement by Share-based Payment Award, Vesting Rate Share-based Compensation Arrangement by Share-based Payment Award, Vesting Rate TXNM to PNM TXNM To PNM [Member] TXNM to Pnm [Member] Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Regulatory liabilities Regulatory Liability, Noncurrent Entity Address, State or Province Entity Address, State or Province Finance cash flows from financing leases Finance Lease, Principal Payments Antidilutive Security, Excluded EPS Calculation [Table] Antidilutive Security, Excluded EPS Calculation [Table] Total current liabilities Current liabilities Liabilities, Current Individual: Individual [Axis] Consultant fees Sales And Use Tax Refund, Consultant Fees Sales And Use Tax Refund, Consultant Fees Financing leases Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Dividends paid Payments of Ordinary Dividends, Common Stock Entities [Table] Entities [Table] Net plant in service and plant held for future use Public Utilities Property Plant And Equipment In Service, Net Public Utilities Property Plant And Equipment In Service, Net Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Repayment of long-term debt Repayments of Long-Term Debt Entity Interactive Data Current Entity Interactive Data Current Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Purchase of common stock Public Utilities, Purchase Of Common Stock, Amount Public Utilities, Purchase Of Common Stock, Amount Catastrophic Event [Domain] Catastrophic Event [Domain] Nuclear Decommissioning Trust Nuclear Decommissioning Trust [Member] Nuclear Decommissioning Trust [Member] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Schedule of Regulatory Rate Matters [Axis] Schedule of Regulatory Rate Matters [Axis] Schedule of Regulatory Rate Matters [Axis] Other deferred credits Finance Lease, Liability, Deferred Credits, Other Finance Lease, Liability, Deferred Credits, Other Schedule of Weighted-Average Assumptions and Restricted Stock Awards Activity Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block] Cost related to investment Investment Owned, Cost Investment securities Investment securities Marketable Securities Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Equity contribution from parent Proceeds from Contributions from Parent Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Annual lease payments Lessee, Right-Of-Way Lease, Annual Payments Annual lease payments Derivative agreements Derivative, Number of Agreements Entered Derivative, Number of Agreements Entered 2028 Finance Lease, Liability, to be Paid, Year Two Wholesale energy sales Wholesale Energy Sales [Member] Wholesale Energy Sales Customer [Domain] Customer [Domain] Entity Central Index Key Entity Central Index Key PEO Name PEO Name Conversion price (in dollars per share) Debt Instrument, Convertible, Conversion Price Cumulative preferred stock of subsidiary, shares issued (in shares) Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Shares Issued Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Shares Issued Electric Operating Revenues Operating revenues Total Electric Operating Revenues Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Accrued interest and taxes Accrued Interest Accrued Interest Later years Lessee, Operating Lease, Liability, to be Paid, after Year Four Lessee, Operating Lease, Liability, to be Paid, after Year Four Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Customer deposits Contract with Customer, Liability, Current Exercise Price Award Exercise Price Long-term Contract for Purchase of Electric Power [Domain] Long-Term Contract for Purchase of Electric Power [Domain] Entity Filer Category Entity Filer Category Navajo Nation Navajo Nation [Member] Navajo Nation [Member] Common stock, no par value (in dollars per share) Common Stock, No Par Value Subsequent Event Type [Axis] Subsequent Event Type [Axis] Commitment to innovative technologies Public Utilities, Innovative Technologies Commitment, Amount Public Utilities, Innovative Technologies Commitment, Amount Long-term Debt, net of Unamortized Premiums, Discounts, and Debt Issuance Costs (includes $320,752 and $324,531 related to ETBC I) Long-term debt, net of unamortized premiums, discounts, and debt issuance costs Long-term Debt Long-Term Debt, Excluding Current Maturities Nonrelated Party Nonrelated Party [Member] Balance Sheet Location [Axis] Statement of Financial Position Location, Balance [Axis] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Debt Maturities [Table] Debt Maturities [Table] Debt Maturities [Table] Entity Address, Address Line One Entity Address, Address Line One Coal-Fired Electricity Generating Facility Demolition And Remediation Ordinance Coal-Fired Electricity Generating Facility Demolition And Remediation Ordinance [Member] Coal-Fired Electricity Generating Facility Demolition And Remediation Ordinance Net Earnings Per Share of Common Stock: Earnings Per Share, Basic And Diluted, EPS [Abstract] Earnings Per Share, Basic And Diluted, EPS Financial Statement Location [Axis] Financial Statement Location [Axis] Financial Statement Location [Axis] AOCI Total AOCI Attributable to Parent [Member] Allowance for uncollectible accounts Accounts Receivable, Allowance for Credit Loss, Current Otero, San Miguel and Luna Counties Otero, San Miguel, And Luna Counties [Member] Otero, San Miguel, And Luna Counties Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Coal supply Coal Supply [Member] Coal Supply [Member] Uncategorized collective investment trust Collective Investment Trust [Member] Collective Investment Trust Fair Value as of Grant Date Award Grant Date Fair Value Reclassification adjustment for gains (losses) included in net earnings, income tax (expense) benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Market-Based Shares Market-Based Shares [Member] Market-Based Shares [Member] TXNM common stockholders’ equity: PNM common stockholder’s equity: Common Stockholder’s Equity: Company Common Stockholders Equity Company Common Stockholders Equity Total financing lease expense Finance Lease, Cost Finance Lease, Cost Restricted stock (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Title of Individual [Domain] Title and Position [Domain] Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unrecognized expense related to stock awards Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Related Party Transaction [Line Items] Related Party Transaction [Line Items] Number of nuclear power plants owned Number Of Nuclear Power Plants Owned Number Of Nuclear Power Plants Owned Document Quarterly Report Document Quarterly Report Performance period Performance Period Performance period Fair value of long-term debt Long-Term Debt, Fair Value TXNM ATM Program TXNM ATM Program [Member] TXNM ATM Program Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Counterparty Name [Domain] Counterparty Name [Domain] Transmission by others Electric Transmission [Member] 2028 Lessee, Operating Lease, Liability, to be Paid, Year Two Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Zero Point Eight Seven Five Percent, Pollution Control Revenue Bonds Due October Twenty Twenty Six Zero Point Eight Seven Five Percent, Pollution Control Revenue Bonds Due October Twenty Twenty Six [Member] Zero Point Eight Seven Five Percent, Pollution Control Revenue Bonds Due October Twenty Twenty Six Results of Operations Variable Interest Entity, Statement Of Operation [Abstract] Variable Interest Entity, Statement Of Operation [Abstract] Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Non-PEO NEO Non-PEO NEO [Member] Letters of credit outstanding Letters of Credit Outstanding, Amount Lease to be executed, term of contract Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Other operating leases Other Operating Leases [Member] Other Operating Leases Sale of Stock [Axis] Sale of Stock [Axis] Program costs related to energy efficiency, number of programs Public Utilities, Program Costs Related To Energy Efficiency, Number Of Programs Public Utilities, Program Costs Related To Energy Efficiency, Number Of Programs Accrued interest and taxes Increase Decrease In Accrued Interest And Taxes Increase (Decrease) In Accrued Interest And Taxes Aggregate amount of all risk insurance Public Utilities, Aggregate Amount of All Risk Insurance Public Utilities, Aggregate Amount of All Risk Insurance Award Type [Domain] Award Type [Domain] 2027 Lessee, Operating Lease, Liability, to be Paid, Year One Goodwill Goodwill Disclosure [Text Block] Non-controlling interest in Valencia Owners’ Equity – Non-controlling Interest Equity, Attributable to Noncontrolling Interest Equity Awards Adjustments Equity Awards Adjustments [Member] WEB LOC Facility WFB LOC Facility [Member] WFB LOC Facility Other, net Other Noncash Income (Expense) Requested recovery rate TNMP Rate Base Review, Requested Recovery Rate TNMP Rate Base Review, Requested Recovery Rate Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Other income Other Income Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Retirement Plan Type [Domain] Retirement Plan Type [Domain] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Accumulated Other Comprehensive Income (Loss) [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Lease to be executed, fixed consideration Lessee, Operating Lease, Lease Not Yet Commenced, Fixed Consideration Lessee, Operating Lease, Lease Not Yet Commenced, Fixed Consideration Remainder of 2026 Finance Lease, Liability, to be Paid, Remainder of Fiscal Year Accumulated other comprehensive income (loss), net of income taxes Accumulated Other Comprehensive Income (Loss), Net of Tax Merger agreement, anniversary period Merger Agreement, Merger Close Period Merger Agreement, Merger Close Period Financial Instruments [Domain] Financial Instruments [Domain] Performance Shares Performance Shares [Member] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Reclassification adjustment for amortization of losses recognized in net earnings, net of income tax (expense) benefit of $(12) and $0 Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Materials, supplies, and fuel stock Materials and supplies Inventory, Net Minimum Minimum [Member] Company Selected Measure Name Company Selected Measure Name Fair Value Measurement [Domain] Fair Value Measurement [Domain] Rate credits Public Utilities, Annual Rate Credits Public Utilities, Annual Rate Credits Financing Debt Disclosure [Text Block] Losses on investment securities Gain (Loss) on Sale of Investments Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Purchase Commitment, Excluding Long-term Commitment [Domain] Purchase Commitment, Excluding Long-Term Commitment [Domain] Accounts payable Payable Accounts Payable, Current Operating cash flows from operating leases Operating Lease, Payments Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Sale of equity method investee, tax effect Sale Of Equity Method Investee, Tax Effect Sale Of Equity Method Investee, Tax Effect Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Deferred Charges and Other Assets: Other Assets, Noncurrent [Abstract] Average Shares – Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Derivative [Table] Derivative [Table] Entity Small Business Entity Small Business Non-utility property Finance Lease, Right-Of-Use Asset, Gross Finance Lease, Right-Of-Use Asset, Gross Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Convertible Notes Five Point Seven Five Percent, Convertible Notes Due June Twenty Fifty Four [Member] Five Point Seven Five Percent, Convertible Notes Due June Twenty Fifty Four Document Transition Report Document Transition Report After 1 year through 5 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Total minimum lease payments Finance Lease, Liability, to be Paid Underlying Securities Award Underlying Securities Amount Gross realized gains Debt Securities, Available-for-Sale, Realized Gain Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Income Taxes Income Tax Disclosure [Text Block] Revolving credit facilities borrowings Revolving credit facilities borrowings Proceeds from Lines of Credit Vested awards of restricted stock (in shares) Weighted Average Number of Shares, Restricted Stock Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Short-term lease expense Short-Term Lease, Cost Other Deferred Charges Other Deferred Costs Net Including Deferred Finance Costs [Member] Other Deferred Costs Net Including Deferred Finance Costs Total equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Forward Contract Indexed to Issuer's Equity [Line Items] Forward Contract Indexed to Issuer's Equity [Line Items] Document Type Document Type Earnings Per Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Paid-in-capital Additional Paid in Capital Product and Service [Axis] Product and Service [Axis] Reclamation trust funding, 2027 Reclamation Trust Funding, Year One Reclamation Trust Funding, Year One Total other property and investments Total Other Property And Investments Total Other Property And Investments Variable lease expense Variable Lease, Cost Total revenues from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Less accumulated depreciation and amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Estimated project costs Estimated Project Costs Estimated Project Costs Total current assets Current assets Assets, Current Reclamation trust funding, 2026 Reclamation Trust Funding, Remainder Of The Year Reclamation Trust Funding, Remainder Of The Year Statistical Measurement [Axis] Statistical Measurement [Axis] Loss contingency accrual Loss Contingency Accrual Outstanding during period (in shares) Weighted Average Number of Shares Issued, Basic Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Energy Storage Battery Storage Facilities [Member] Battery Storage Facilities Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Net earnings (losses) available for common stock Net Earnings Attributable to TXNM Net Income (Loss) Available to Common Stockholders, Basic Regulatory assets Regulatory Asset, Current Entity Information [Line Items] Entity Information [Line Items] Current Liabilities: Liabilities, Current [Abstract] Level 1 Fair Value, Inputs, Level 1 [Member] Contract assets Commodity Contract Asset, Current Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] Diluted (in dollars per share) Earnings Per Share, Diluted Unamortized cost, right-of-way lease payments Unamortized Cost Of Prepaid Right-Of-Way Agreements Unamortized Cost Of Prepaid Right-Of-Way Agreements Accrued interest and taxes Accrued Interest And Taxes Payable Accrued Interest And Taxes Payable Accounts receivable, net of allowance for credit losses of $1,498 and $1,394 Accounts receivable, net of allowance for credit losses of $1,498 and $1,394 Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Supplemental schedule of noncash investing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Offset related interest expense Sales And Use Tax Refund, Offset Related Interest Expense Sales And Use Tax Refund, Offset Related Interest Expense Distribution agreement Sale Of Stock, Distribution Agreement, Aggregate Value Sale Of Stock, Distribution Agreement, Aggregate Value Schedule of Gross Realized Gains and Losses Schedule of Realized Gain (Loss) [Table Text Block] Dividends declared on preferred stock Dividends, Preferred Stock, Cash Sales and use tax refund Sales And Use Tax Refund, Claim Sales And Use Tax Refund, Claim Lessee, operating lease, unguaranteed residual value Lessee, Operating Lease, Unguaranteed Residual Value Lessee, Operating Lease, Unguaranteed Residual Value Operating leases: Operating Lease, Assets And Liabilities, Lessee [Abstract] Operating Lease, Assets and Liabilities, Lessee [Abstract] Hurricane Hurricane [Member] RFP Request, Period Two RFP Request, Period Two [Member] RFP Request, Period Two Other Deferred Credits Other Deferred Credits [Member] Other Deferred Credits [Member] Residential rate credits, payment period Public Utilities, Annual Rate Credits, Period Public Utilities, Annual Rate Credits, Period Annual Increase in Revenue Public Utilities, Actual Annual Increase Annual Distribution Revenue Requirement Public Utilities, Actual Annual Increase Annual Distribution Revenue Requirement Expected quarterly dividends per share (in dollars per share) Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Expected Quarterly Dividend Rate Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Expected Quarterly Dividend Rate Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Public authority Retail Electric, Public Authority Customers [Member] Retail Electric, Public Authority Customers Palo Verde Nuclear Generating Station Palo Verde Nuclear Generating Station [Member] Palo Verde Nuclear Generating Station [Member] Net other income and (deductions) Other Income Deductions Excluding Interest Other Income Deductions Excluding Interest Less: Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Income taxes paid (refunded), net Income taxes paid (refunded), net Income Taxes Paid, Net MUFG Securities EMEA plc MUFG Securities EMEA plc (b) [Member] MUFG Securities EMEA plc (b) Total minimum lease payments Lessee, Operating Lease, Liability, to be Paid Net increase in unrealized holding gains arising during the period, net of income tax (expense) of $0 and $(68) Net increase in unrealized holding gains arising during the period, net of income tax (expense) of $0 and $(68) OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Grid modernization, initial term Public Utilities, Grid Modernization, Initial Term Public Utilities, Grid Modernization, Initial Term Preferred Stock Dividend Requirements of Subsidiary Subsidiary preferred stock dividends Preferred Stock Dividend Requirements of Subsidiary Preferred stock cash dividend declared by a subsidiary of the entity during the period. This element includes paid and unpaid dividends declared during the period. Miscellaneous Miscellaneous Revenue From Contracts With Customers [Member] Miscellaneous Revenue From Contracts With Customers [Member] Valencia’s transactions with its owner Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Forward contracts, issuance costs Forward Contracts, Issuance Costs Forward Contracts, Issuance Costs San Juan Generating Station and Four Corners San Juan Generating Station And Four Corners [Member] San Juan Generating Station And Four Corners [Member] Disbursements by employer, year one through four Defined Benefit Plan, Estimated Future Employer Disbursements, Year One Through Four Defined Benefit Plan, Estimated Future Employer Disbursements, Year One Through Four Allowance for equity funds used during construction Allowance for equity funds used during construction and other, net Increase (Decrease) in Allowance for Equity Funds Used During Construction Expiration Date Trading Arrangement Expiration Date Short-Term Lease Type [Domain] Short-Term Lease Type [Domain] Short-Term Lease Type [Domain] Public Utilities, Commitments and Contingencies [Table] Public Utilities, Commitments and Contingencies [Table] Public Utilities, Commitments and Contingencies [Table] Amount of related party transaction Related Party Transaction, Amounts of Transaction Net (losses) on equity securities still held Equity Securities, FV-NI, Unrealized Gain (Loss) Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] San Juan Generating Station San Juan Generating Station [Member] San Juan Generating Station [Member] Entity Current Reporting Status Entity Current Reporting Status Request for proposal, new energy resource, megawatts Request For Proposal, New Energy Resource, Megawatts Request For Proposal, New Energy Resource, Megawatts Derivative [Line Items] Derivative [Line Items] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Consolidated Entities [Domain] Consolidated Entities [Domain] Assets and Liabilities, Lessee [Table] Assets And Liabilities, Lessee [Table] Assets and Liabilities, Lessee [Table] PNM to TXNM PNM To TXNM [Member] PNM to TXNM [Member] Schedule of Available-for-sale Securities, Major Types of Debt and Equity Securities [Axis] Financial Instrument [Axis] Financial Instrument [Axis] Other deferred charges Other Deferred Costs Net Including Deferred Finance Costs Other Deferred Costs Net Including Deferred Finance Costs Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Lease, Cost [Line Items] Lease, Cost [Line Items] [Line Items] for Lease, Cost [Table] Cumulative preferred stock of subsidiary, shares authorized (in shares) Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Shares Authorized Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Shares Authorized Asset retirement obligations Asset Retirement Obligations, Noncurrent Long-term borrowings Proceeds from Issuance of Long-Term Debt Interest Charges Interest Charges Interest Expense, Operating and Nonoperating Current Fiscal Year End Date Current Fiscal Year End Date Other related expenses Sales And Use Tax Refund, Other Related Expenses Sales And Use Tax Refund, Other Related Expenses Restricted Stock, Weighted- Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Extension period Debt Instrument, Extension Period Debt Instrument, Extension Period Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Non-cash information related to right-of-use assets obtained in exchange for lease obligations: Right-Of-Use Asset Obtained In Exchange For Lease Liability [Abstract] Right-Of-Use Asset Obtained In Exchange For Lease Liability [Abstract] PNM Revolving Credit Facility PNM Revolving Credit Facility [Member] PNM Revolving Credit Facility Proceeds from sales of investment securities Proceeds from Sale and Maturity of Marketable Securities Equity securities: Equity Securities, FV-NI, Current Transmission Electric Transmission Service [Member] Electric Transmission Service Dilutive Effect of Common Stock Equivalents: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Forward contracts, net cash proceeds Forward Contract Indexed to Equity, Settlement, Cash, Amount Lease Commitments Lessee, Operating Leases [Text Block] Net cash flows from financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation NMPRC approved credit facility Debt Instruments, NMPRC Approved Credit Facility Debt Instruments, NMPRC Approved Credit Facility Measure: Measure [Axis] Pension Liability Adjustment: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract] Short-Term Lease Type [Axis] Short-Term Lease Type [Axis] Short-Term Lease Type Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Energy costs Cost of energy Cost of Product and Service Sold Reclamation costs percentage Reclamation Costs, Redemption Percentage Reclamation Costs, Redemption Percentage Program costs related to energy efficiency, in year two Public Utilities, Program Costs Related To Energy Efficiency, Year Two Public Utilities, Program Costs Related To Energy Efficiency, Year Two Initial forward price (in shares) Settlement shares (in shares) Forward Contract Indexed to Issuer's Equity, Shares Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Royal Bank of Canada Royal Bank of Canada [Member] Royal Bank of Canada Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Risk-free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] Entity Tax Identification Number Entity Tax Identification Number Schedule of Summarized Financial Information Schedule of Variable Interest Entities [Table Text Block] Administrative and general - direct General And Administrative Expense, Direct General And Administrative Expense, Direct Amounts capitalized Operating Lease, Capitalized Costs Operating Lease, Capitalized Costs Performance Equity Plan Performance Equity Plan [Member] Performance Equity Plan [Member] Classification of Mine [Axis] Classification of Mine [Axis] Classification of Mine [Axis] Common stock, shares issued (in shares) Common Stock, Shares, Issued Total deferred credits and other liabilities Liabilities, Other than Long-Term Debt, Noncurrent Operating leases Operating Lease, Weighted Average Remaining Lease Term Period of time for proposed return to customers the benefit of the reduction in federal corporate income tax rate Public Utilities, Proposed Term to Provide Customers with Benefits Related to Reduction in Federal Corporate Income Tax Rate Public Utilities, Proposed Term To Provide Customers With Benefits Related To Reduction In Federal Corporate Income Tax Rate Restricted Cash included in Other Current Assets and Other Deferred Charges on Condensed Consolidated Balance Sheets: Restricted Cash [Abstract] Dividends declared Dividends Payable, Current TNMP 2025 Bond At Five Point One Nine Percent TNMP February 2025 Bond At Five Point One Nine Percent, Due April 1, 2031 [Member] TNMP February 2025 Bond At Five Point One Nine Percent, Due April 1, 2031 Convertible Notes Convertible Debt Securities [Member] Interest charges Interest Expense, Nonoperating Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Security Exchange Name Security Exchange Name Annual funding post-term reclamation trust, remainder of year Public Utilities, Annual Funding Post-Term Reclamation Trust, Remainder Of Year Public Utilities, Annual Funding Post-Term Reclamation Trust, Remainder Of Year Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant [Domain] Executive Retirement Program Other Pension Plan [Member] Financing capacity Line of Credit Facility, Maximum Borrowing Capacity Preferred Stock Dividend Requirements of Subsidiary Preferred Stock Dividend Requirements Dividends, Preferred Stock Prepaid assets Prepaid Expense, Current Operating Expenses: Operating Expenses [Abstract] Other current liabilities Other Liabilities, Current Accrued pension liability and postretirement benefit cost Liability, Defined Benefit Plan, Noncurrent Statement [Line Items] Statement [Line Items] Unprotected excess deferred income taxes Public Utilities, Unprotected Excess Deferred Income Taxes Public Utilities, Unprotected Excess Deferred Income Taxes Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent Common Stock Corporate stocks, common Common Stock [Member] Released (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Financing Finance Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Change in Cash, Cash Equivalents, and Restricted Cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Significant Accounting Policies and Responsibility for Financial Statements Significant Accounting Policies [Text Block] Energy efficiency cost recovery Energy Efficiency Cost Recovery Factor Energy Efficiency Cost Recovery Factor Statistical Measurement [Domain] Statistical Measurement [Domain] Other Current Assets Other Current Assets [Member] Business Combination [Abstract] At beginning of period At end of period Restricted Cash, Current Remainder of 2026 Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Regulatory and Rate Matters Regulatory And Rate Matters [Text Block] Regulatory And Rate Matters [Text Block] Leases [Abstract] Leases [Abstract] Cash used to support bank letter or credit arrangement Cash Used To Support Bank Letter Or Credit Arrangement Cash used to support bank letter or credit arrangement Notes Payable to Banks Notes Payable to Banks [Member] Insurance Carrier [Domain] Insurance Carrier [Domain] Insurance Carrier [Domain] Accounts payable Increase (Decrease) in Accounts Payable Net Earnings Attributable to TXNM per Common Share: Income Loss From Continuing Operations Attributable To Parent Per Share [Abstract] Income Loss From Continuing Operations Attributable To Parent Per Share [Abstract] Leases, Operating [Table] Leases, Operating [Table] Leases, Operating [Table] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic (in dollars per share) Earnings Per Share, Basic Commercial Paper Commercial Paper [Member] Equity contribution from parent Adjustments To Additional Paid In Capital, Parent Contributions Adjustments To Additional Paid In Capital, Parent Contributions Nuclear spent fuel and waste disposal Nuclear Spent Fuel And Waste Disposal [Member] Nuclear Spent Fuel And Waste Disposal [Member] Grid modernization, investment increase period Public Utilities, Grid Modernization, Investment Increase Period Public Utilities, Grid Modernization, Investment Increase Period TXNM TXNM [Member] TXNM Unbilled revenues Unbilled Receivables, Current Total Other Comprehensive Income Total other comprehensive income Other Comprehensive Income (Loss), Net of Tax Schedule of Financial Information by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Short-term debt Balance Outstanding Short-Term Debt Threshold percentage of stock price trigger Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Long-term Contract for Purchase of Electric Power [Axis] Long-Term Contract for Purchase of Electric Power [Axis] Classification of Mine [Domain] Classification of Mine [Domain] Classification of Mine [Domain] Annual funding post-term reclamation trust, year two Public Utilities, Annual Funding Post-Term Reclamation Trust, Year Two Public Utilities, Annual Funding Post-Term Reclamation Trust, Year Two Liability insurance coverage Public Utilities, Liability Insurance Coverage Public Utilities, Liability Insurance Coverage Number of shares vested at one-time sign-on (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Granted and Vested, During Period Share-based Compensation Arrangement by Share-based Payment Award, Granted and Vested, During Period 2029 Finance Lease, Liability, to be Paid, Year Three Schedule of Regulatory Rate Matters [Domain] Schedule of Regulatory Rate Matters [Domain] Schedule of Regulatory Rate Matters [Domain] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Cash and cash equivalents Cash and Cash Equivalents [Member] Valencia Variable Interest Entity, Primary Beneficiary [Member] Energy storage leases Battery Storage Leases [Member] Battery Storage Leases Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] Contribution payment period Public Utilities, Donation Contribution, Payment Period Public Utilities, Donation Contribution, Payment Period Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Grid modernization term Public Utilities, Grid Modernization Term Public Utilities, Grid Modernization Term Current Assets: Assets, Current [Abstract] Total liabilities and stockholders' equity Liabilities and Equity Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Pension Liability Adjustment Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Operating lease, residual value of leased asset Operating Lease, Residual Value of Leased Asset Other Income and Deductions: Other Nonoperating Income (Expense) [Abstract] Program costs related to energy efficiency, in year three Public Utilities, Program Costs Related To Energy Efficiency, Year Three Public Utilities, Program Costs Related To Energy Efficiency, Year Three Threshold consecutive trading days Debt Instrument, Convertible, Threshold Consecutive Trading Days Accounting Policies [Abstract] Accounting Policies [Abstract] Public Utility [Axis] Public Utility [Axis] Grid modernization, maintenance cost Public Utilities, Grid Modernization, Decrease In Operations And Maintenance Cost, Percent Public Utilities, Grid Modernization, Decrease In Operations And Maintenance Cost, Percent Schedule of Future Expected Lease Payments, Operating Lease Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Total fair value of restricted shares that vested Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Dividends Payable [Line Items] Dividends Payable [Line Items] Pay vs Performance Disclosure [Line Items] Lease liabilities Operating Lease, Liability Right-of-way lease payments Lessee, Right-Of-Way Lease, Payments Right-Of-Way Lease Payments Maximum number of shares awarded, remainder of year (in shares) Share-Based Compensation Arrangement By Share-based Payment Award, Number Of Shares Excluded, Remainder Of Year Share-Based Compensation Arrangement By Share-based Payment Award, Number Of Shares Excluded, Remainder Of Year Merger Business Combination [Text Block] Amortization of right-of-use assets Finance Lease, Right-of-Use Asset, Amortization Later years Finance Lease, Liability, to be Paid, after Year Four Finance Lease, Liability, to be Paid, after Year Four Maximum number of shares awarded in year two (in shares) Share-Based Compensation Arrangement By Share-based Payment Award, Maximum Number Of Shares Awarded, In Year Two Share-Based Compensation Arrangement By Share-based Payment Award, Maximum Number Of Shares Awarded, In Year Two Valencia County Valencia County [Member] Valencia County MUFG Securities EMEA plc MUFG Securities EMEA plc (a) [Member] MUFG Securities EMEA plc (a) Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Current installments of long-term debt (includes $7,509 and $7,303 related to ETBC I) Current installments of long-term debt Long-Term Debt, Current Maturities Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount 2029 Lessee, Operating Lease, Liability, to be Paid, Year Three Contributions by employer Defined Benefit Plan, Plan Assets, Contributions by Employer Other liabilities Increase (Decrease) in Other Noncurrent Liabilities Fair Value Adjustment for Cash Flow Hedges: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Comprehensive Income Attributable to TXNM Comprehensive Income (Loss), Net of Tax, Attributable to Parent Energy production costs Electricity, Generation [Member] Name Measure Name Limited Guarantee Limited Guarantee [Member] Limited Guarantee Within 1 year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Accumulated deferred income taxes Deferred Income Tax Liabilities, Net Ratio of debt to capital (less than or equal to) Debt Instrument, Covenant, Debt To Capitalization Ratio Debt Instrument, Covenant, Debt To Capitalization Ratio Unsecured Debt Unsecured Debt [Member] Electric Operating Revenues Results of Operations Variable Interest Entity Operating Revenues Results of Operations Variable Interest Entity Operating Revenues Income Tax Contingency [Table] Income Tax Contingency [Table] Long-term debt Long-Term Debt Grid modernization, revenue Public Utilities, Grid Modernization, Revenue Requirement Year One Public Utilities, Grid Modernization, Revenue Requirement Year One Legal Entity [Axis] Legal Entity [Axis] Total assets Total Assets Assets Public Utility Commission Of Texas Public Utility Commission Of Texas [Member] Public Utility Commission Of Texas Cumulative Preferred Stock of Subsidiary without mandatory redemption requirements ($100 stated value; 10,000,000 shares authorized; issued and outstanding 115,293 shares) Cumulative Preferred Stock without mandatory redemption requirements ($100 stated value; 10,000,000 shares authorized; issued and outstanding 115,293 shares) Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Cumulative Preferred Stock Of Subsidiary Without Mandatory Redemption Requirements Excess return on jurisdictional equity that would require refund Public Utilities, Excess Return On Jurisdictional Equity That Would Require Refund Public Utilities, Excess Return On Jurisdictional Equity That Would Require Refund Released (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Executive Management [Member] Geographical [Domain] Geographical [Domain] Securitized Cost (included in Regulatory assets - Deferred) Securitized Cost, Noncurrent Securitized Cost, Noncurrent Cash paid for amounts included in the measurement of lease liabilities: Cash Flow, Lessee [Abstract] Cash Flow, Lessee [Abstract] Cash Flows From Operating Activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Other Property and Investments: Other Property And Investments [Abstract] Other Property And Investments [Abstract] Economy energy service Retail Electric, Economy Energy Service Customers [Member] Retail Electric, Economy Energy Service Customers Industrial Retail Electric, Industrial Customers [Member] Retail Electric, Industrial Customers Business combination, cash right per common share (in dollars per share) Business Combination, Cash Right Per Common Share Business Combination, Cash Right Per Common Share Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] 2027 Finance Lease, Liability, to be Paid, Year One Other investments Other Investments Dividends Declared per Common Share (in dollars per share) Dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Capital investment Investment Owned, Balance, Principal Amount Energy Efficiency and Load Management Program Energy Efficiency and Load Management Program [Member] Energy Efficiency and Load Management Program Operating leases additions Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Financing lease cost: Lease, Cost [Abstract] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Grid modernization investment Public Utilities, Grid Modernization Investment Public Utilities, Grid Modernization Investment Level 2 Fair Value, Inputs, Level 2 [Member] TXNM to TNMP TXNM To TNMP [Member] TXNM to Tnmp [Member] Payment for fixed costs Long Term Contract For Purchase of Electric Power Fixed Costs Long Term Contract For Purchase of Electric Power Fixed Charges Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Combination [Domain] Business Combination [Domain] Nuclear fuel, net of accumulated amortization of $32,070 and $27,953 Nuclear fuel, net of accumulated amortization of $32,070 and $27,953 Nuclear Fuel, Net of Amortization Related Party Related Party [Member] Plan Name [Axis] Plan Name [Axis] PEO PEO [Member] Annual Increase in Revenue Public Utilities, Increase Annual Transmission Service Revenue Public Utilities, Increase Annual Transmission Service Revenue Number of megawatts available in purchase power agreement (in megawatts) Public Utilities, Number Of Megawatts Available In Purchase Power Agreement Public Utilities, Number Of Megawatts Available In Purchase Power Agreement Schedule of Maturities of Debt Securities Investments Classified by Contractual Maturity Date [Table Text Block] Interest income Investment Income, Interest System Resiliency Plan System Resiliency Plan [Member] System Resiliency Plan Corporate and Other Corporate Segment and Other Operating Segment [Member] Changes in certain assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Expected volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Total operating expenses Operating expenses Utilities Operating Expense Retained Earnings Retained Earnings [Member] Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Cash, Cash Equivalents, and Restricted Cash at Beginning of Period Cash, Cash Equivalents, and Restricted Cash at End of Period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Restricted Shares and Performance Based Shares Restricted Stock and Performance Shares [Member] Restricted Stock and Performance Shares [Member] Purchases of investment securities Payments to Acquire Marketable Securities Sale of Stock [Domain] Sale of Stock [Domain] Bank Of America, N.A. Bank Of America, N.A. (b) [Member] Bank Of America, N.A. (b) Accumulated depreciation, nuclear fuel Accumulated Amortization Nuclear Fuel Accumulated amortization, nuclear fuel Product and Service [Domain] Product and Service [Domain] Available-for-sale debt securities: Debt Securities, Available-for-Sale [Abstract] SJGS Decommissioning Trust SJGS Decommissioning Trust [Member] SJGS Decommissioning Trust Diluted (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Total TXNM Common Stockholders’ Equity Total PNM Common Stockholder’s Equity Parent [Member] Net Earnings (Losses) Net earnings Net earnings before subsidiary preferred stock dividends Net Earnings (Loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Business Combination [Table] Business Combination [Table] Commercial providers Commercial Providers [Member] Commercial Providers [Member] Real estate funds Other Real Estate Long-term contract option to purchase, purchase price - percentage of adjusted NBV Long Term Contract Option To Purchase, Purchase Price - Percentage Of Adjusted NBV Long term contract option to purchase, purchase price - percentage of adjusted NBV City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Equity ratio, percent TNMP Rate Base Review, Requested On Equity Ratio, Percent TNMP Rate Base Review, Requested On Equity Ratio, Percent Cash Flows From Investing Activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Administrative and general General and Administrative Expense Short-term borrowings (repayments) – affiliate, net Proceeds from (Repayments of) Related Party Debt Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Energy efficiency cost recovery factor, performance bonus Energy Efficiency Cost Recovery Factor, Performance Bonus Energy Efficiency Cost Recovery Factor, Performance Bonus Related Party Transactions [Abstract] Related Party Transactions [Abstract] Net gains (losses) on debt securities Debt Securities, Realized Gain (Loss) Amortization of net (gain) loss Defined Benefit Plan, Amortization of Gain (Loss) Total lease expense for the period Lease, Cost TXNM 2026 ATM Program TXNM 2026 ATM Program [Member] TXNM 2026 ATM Program Goodwill Goodwill Estimate of possible loss Loss Contingency, Estimate of Possible Loss Schedule of Components of Lease Expense Lease, Cost [Table Text Block] (Losses) on investment securities Gain (Loss) on Investments Equipment Equipment [Member] Deferred Credits and Other Liabilities: Other Liabilities, Noncurrent [Abstract] Reclassification adjustment for amortization of experience losses recognized as net periodic benefit cost, net of income tax (benefit) of $(217) and $(349) Reclassification adjustment for amortization of experience losses recognized as net periodic benefit cost, net of income tax (benefit) of $(217) and $(349) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Supplemental Cash Flow Disclosures: Supplemental Cash Flow Information [Abstract] Estimated disbursement by employer, current year Defined Benefit Plan, Plan Assets, Estimated Disbursement By Employer, Current Year Defined Benefit Plan, Plan Assets, Estimated Disbursement By Employer, Current Year Other Performance Measure, Amount Other Performance Measure, Amount U.S. government US Treasury and Government [Member] (Increase)/decrease in other than temporary losses of available-for-sale securities, net portion recognized in earnings (Increase)/Decrease In Other Than Temporary Losses, Investments, Portion Recognized In Earnings, Net, Available-For-Sale Securities (Increase)/Decrease In Other Than Temporary Losses, Investments, Portion Recognized In Earnings, Net, Available-For-Sale Securities Bank Of America, N.A. Bank Of America, N.A. (a) [Member] Bank Of America, N.A. (a) Related Party [Domain] Related and Nonrelated Parties [Domain] Total net (losses) on equity securities Equity Securities, FV-NI, Gain (Loss) Restricted cash Restricted Cash Lease Commitments Lessee, Finance Leases [Text Block] Nuclear plant Nuclear Plant [Member] Other current assets Other Assets, Current Entity [Domain] Entity [Domain] Long-term contract option to purchase, purchase price - percentage of FMV Long Term Contract Option To Purchase, Purchase Price - Percentage Of FMV Long term contract option to purchase, purchase price - percentage of FMV Net cash flows used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Interest paid, net of amounts capitalized Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Operating lease right-of-use assets, net of accumulated amortization Operating lease assets, net of amortization Operating Lease, Right-of-Use Asset Effective tax rate Effective Income Tax Rate Reconciliation, Percent PNM Public Service Company of New Mexico Public Service Company of New Mexico [Member] Public Service Company of New Mexico [Member] Total operating lease expense Operating Lease, Cost Profit incentive sliding scale multiplier Public Utilities, Profit Incentive Sliding Scale Multiplier Public Utilities, Profit Incentive Sliding Scale Multiplier Plan Name [Domain] Plan Name [Domain] Carrying Amount Reported Value Measurement [Member] Period of time stock expense is expected to be recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Equity: Equity [Abstract] Net (losses) on investment securities Debt and Equity Securities, Gain (Loss) Segment Information Segment Reporting Disclosure [Text Block] Schedule of Goodwill [Table] Goodwill [Table] Residential Retail Electric, Residential Customers [Member] Retail Electric, Residential Customers Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Estimated employer contributions for remainder of fiscal year through year four Defined Benefit Plan, Estimated Future Employer Contributions Remainder of Fiscal Year Through Year Four Defined Benefit Plan, Estimated Future Employer Contributions Remainder of Fiscal Year Through Year Four Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Approved Increase in Rate Base Approved Increase in Rate Base Public Utilities, Approved Rate Increase (Decrease), Amount Financial Position Variable Interest Entity, Statement Of Financial Position [Abstract] Variable Interest Entity, Statement Of Financial Position Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Corporate and other Other Debt Obligations [Member] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Awards of common stock Stock Repurchased During Period, Value Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Additions to utility plant and non-utility plant Utility plant additions Payments to Acquire Productive Assets Depreciation and amortization Depreciation, Depletion and Amortization Projects are estimated to cost Public Utilities, Regulatory Assets Expected Cost Of Projects Public Utilities, Regulatory Assets Expected Cost 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Compensation Share-Based Payment Arrangement [Text Block] Cash Flow, Lessee [Table] Cash Flow, Lessee [Table] Cash Flow, Lessee [Table] Total deferred charges and other assets Total Deferred Charges And Other Assets Total Deferred Charges And Other Assets ASSETS Assets [Abstract] Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Components of Net Periodic Benefit Cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Debt Instrument [Axis] Debt Instrument [Axis] Forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Pension and Other Postretirement Benefit Plans Retirement Benefits [Text Block] Business Combination [Line Items] Business Combination [Line Items] Credit Facility [Domain] Credit Facility [Domain] Debt Maturities [Line Items] Debt 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(c) [Member] Bank Of America, N.A. (c) Reclamation trust funding, 2028 Reclamation Trust Funding, Year Two Reclamation Trust Funding, Year Two Commitments and Contingencies Related to the Environment And Other [Domain] Commitments and Contingencies Related to the Environment And Other, Nature [Domain] Commitments and Contingencies Related to the Environment And Other, Nature Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Geographical [Axis] Geographical [Axis] Scheduled payments Debt Instrument, Periodic Payment Schedule of Interim Distribution Rate Increases Schedule Of Interim Distribution Rate Increases [Table Text Block] Schedule Of Interim Distribution Rate Increases Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Valencia’s transactions with its owner Proceeds (Payments) Of Ordinary Dividends, Noncontrolling Interest Proceeds (Payments) Of Ordinary Dividends, Noncontrolling Interest Refunds paid under transmission interconnection and security deposit 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Unrealized Gains Debt Securities, Available-for-Sale, Unrealized Gain Financial Statement Location [Domain] Financial Statement Location [Domain] Financial Statement Location [Domain] Utility Plant: Public Utilities, Property, Plant and Equipment [Abstract] PNM 2025 Bond At Five Point Seven Five, Due June Twenty Thirty Two PNM April 2025 SUNs At Five Point Seven Five, Due June Twenty Thirty Two [Member] PNM April 2025 SUNs At Five Point Seven Five, Due June Twenty Thirty Two Number of megawatts purchased (in megawatts) Number Of Mega Watts Purchased Number Of Mega Watts Purchased Short-term Debt, Type [Axis] Short-Term Debt, Type [Axis] Insurance Carrier [Axis] Insurance Carrier [Axis] Insurance Carrier [Axis] RFP Request, Period One RFP Request, Period One [Member] RFP Request, Period One Customer related expenses Customer Related Expenses Customer Related Expenses Award Timing Disclosures [Line Items] Economic development fund Public Utilities, Economic Development Fund, Amount 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[Line Items] Segment Reporting Information [Line Items] Awards of common stock Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Accounts receivable Contract with Customer, Asset, after Allowance for Credit Loss First Mortgage Bonds Due 2029 First Mortgage Bonds Due Twenty Twenty Nine [Member] First Mortgage Bonds Due Twenty Twenty Nine Schedule of Assets and Liabilities, Lessee Assets And Liabilities, Lessee [Table Text Block] Assets and Liabilities, Lessee [Table Text Block] PNM 2025 Term Loan PNM 2025 Term Loan [Member] PNM 2025 75 Million Term Loan Customer [Axis] Customer [Axis] Total operating expenses Operating Income (Loss) Line of credit Line of Credit [Member] Retained earnings Retained Earnings (Accumulated Deficit) Program costs related to energy efficiency, in year one Public Utilities, Program Costs Related To Energy Efficiency, Year One Public Utilities, Program Costs Related To Energy Efficiency, Year One Long-term contract option to purchase, ownership percentage (up to) Long Term Contract Option To Purchase, Ownership Percentage Long term contract option to purchase, ownership percentage Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Fair Value Adjustment for Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Net other income and deductions Other Nonoperating Income (Expense) Statement [Table] Statement [Table] Assets and Liabilities, Lessee [Line Items] Assets And Liabilities, Lessee [Line Items] [Line Items] for Assets 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Charitable Fund Payment Period Public Utilities, Charitable Fund Payment Period Purchased through May 2028 Purchased Through May 30, 2028 [Member] Purchased Through May 30, 2028 [Member] Cost of energy Electric operating revenues Electricity [Member] Amendment Flag Amendment Flag Available-for-Sale Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Other deferred credits Deferred Credits and Other Liabilities, Noncurrent OPEB Plan Other Postretirement Benefits Plan [Member] Termination Date Trading Arrangement Termination Date Amounts capitalized Finance Lease, Capitalized Costs Finance Lease, Capitalized Costs Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Operating leases Operating Lease, Weighted Average Discount Rate, Percent Dividends Payable [Table] Dividends Payable [Table] Average Shares – Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Schedule of Computation of 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Arrangement by Share-Based Payment Award [Line Items] Consolidated Entities [Axis] Consolidated Entities [Axis] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Income taxes receivable Income Taxes Receivable, Current Net gains from equity securities sold Equity Securities, FV-NI, Realized Gain (Loss) Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Decrease in accrued plant additions (Increase) Decrease In Capital Expenditures Incurred But Not Yet Paid (Increase) Decrease In Capital Expenditures Incurred But Not Yet Paid Operating cash flows from financing leases Finance Lease, Interest Payment on Liability Regulatory asset, total cost Regulatory Asset Construction work in progress Construction in Progress, Gross Hedge funds Other Multi-Strategy Fund Other Multi-Strategy Fund Schedule of Investment Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Deferred federal, state and 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New Mexico Credit Facility PNM New Mexico Credit Facility [Member] PNM New Mexico Credit Facility Issuance of common stock Stock Issued During Period, Value, New Issues Counterparty Name [Axis] Counterparty Name [Axis] Threshold trading days Debt Instrument, Convertible, Threshold Trading Days Available-for-sale debt securities Available-for-sale debt securities Debt Securities, Available-for-Sale Payment for variable costs Long Term Contract For Purchase of Electric Power Variable Charges Long Term Contract for Purchase of Electric Power Variable Charges Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] PNM 2025 Note Purchase Agreement PNM April 2025 Note Purchase Agreement [Member] PNM April 2025 Note Purchase Agreement