Entity tax identification number Entity Tax Identification Number Note receivable from participant, amortization period EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term Maximum Maximum [Member] Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Registered investment companies Mutual Fund [Member] Employer discretionary contribution EBP, Employer Contribution, Annual Fixed Rate Contribution, Percentage EBP, Employer Contribution, Annual Fixed Rate Contribution, Percentage EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Maximum aggregate equal amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Disclosures EBP, Investment, Fair Value and NAV [Text Block] Participant account, minimum borrowing amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount 55 years of age or older 55 Years Of Age Or Older [Member] 55 Years Of Age Or Older Total investments at fair value Investments at fair value: EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Level 1 Fair Value, Inputs, Level 1 [Member] EBP, Investment, Fair Value and NAV [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Payment of Benefits EBP, Payment to Participant [Policy Text Block] Amendment Flag Amendment Flag Participant contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution Basis of Presentation EBP, Basis of Accounting [Policy Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Percentage of distribution upon participant's termination EBP, Involuntary Cash-out Limit EBP, Involuntary Cash-out Limit EBP, Description of Plan and Accounting Change [Abstract] Receivables: EBP, Receivable [Abstract] EBP, Investment, Fair Value and NAV EBP, Investment, Fair Value and NAV [Table Text Block] Investments [Domain] Investments [Domain] Retirement contribution, percentage EBP, Participant Contribution, Retirement Contribution, Maximum Annual Contribution to Eligible Compensation, Percentage EBP, Participant Contribution, Retirement Contribution, Maximum Annual Contribution to Eligible Compensation, Percentage Schedule H, Line 4i – Schedule of Assets (Held At End of Year) EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] Employer contributions EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash Minimum Minimum [Member] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Investment Type [Axis] Investment Type [Axis] Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Additions to net assets: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Investment Income (Loss), before Investment Expense [Abstract] Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Interest and dividend income from investments EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] EBP 005 EBP 005 [Member] EBP 005 Plan number EBP, Plan Number Other income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Other Investment Income (Loss) EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Plan Description EBP, Description of Plan [Text Block] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Abstract] EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Total additions EBP, Change in Net Asset Available for Benefit, Increase Investment, Identifier [Axis] Investment, Identifier [Axis] Administrative and other expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Investments, fair value EBP, Asset Held for Investment Risks and Uncertainties EBP, Risk and Uncertainty [Policy Text Block] Document Information [Line Items] Document Information [Line Items] 50 - 54 years of age 50 - 54 Years Of Age [Member] 50 - 54 Years Of Age Under 40 years of age Under 40 Years Of Age [Member] Under 40 Years Of Age Contribution of eligible employees EBP, Employer Contribution, Participant Compensation Matched, Percentage EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Level 2 Fair Value, Inputs, Level 2 [Member] EBP, Tax Status [Table] EBP, Tax Status [Table] Net increase in net assets available for benefits EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Party-in-Interest EBP, Related Party and Party-in-Interest Transactions [Text Block] Income: EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment [Abstract] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Employer contributions EBP, Employer Contribution, Receivable Employer contribution withholding percentage EBP, Participant Contribution, Automatic, Deferral Rate Investments, at fair value: EBP, Investment, Fair Value [Abstract] Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Maximum company matching contribution, percentage EBP, Employer Contribution, Maximum Compensation Matched, Percentage EBP, Employer Contribution, Maximum Compensation Matched, Percentage Investments at fair value: EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Tax Status [Abstract] TXNM Energy, Inc. Common Stock Fund EBP, Employer, Common Stock Fund [Member] Contribution of eligible employees compensation EBP, Participant Contribution, Maximum Contribution To Eligible Compensation, Percentage EBP, Participant Contribution, Maximum Contribution To Eligible Compensation, Percentage Participant’s Eligible Compensation Based on Participant’s Age EBP, Contribution [Table Text Block] Administrative Expenses EBP, Expense [Policy Text Block] Notes receivable from participants EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Automatic annual increase deferral rate, percentage EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate, Percentage EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate, Percentage Income Recognition and Investment Valuation EBP, Investment [Policy Text Block] Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] 45 - 49 years of age 45 - 49 Years Of Age [Member] 45 - 49 Years Of Age Document Type Document Type CIK Entity Central Index Key Outstanding loans interest rates EBP, Asset Held for Investment, Participant Loan, Interest Rate Collective investment trusts Common Collective Trust [Member] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] Deductions from net assets: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Notes receivable from participants EBP, Note Receivable from Participant 40 - 44 years of age 40 - 44 Years Of Age [Member] 40 - 44 Years Of Age Range Of Participants [Axis] Range Of Participants [Axis] Range Of Participants Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Entity Registrant Name Entity Registrant Name Total income EBP, Change In Net Asset Available For Benefit, Increase (Decrease) From Income (Loss) On Investment, Including Interest On Participant Loans EBP, Change In Net Asset Available For Benefit, Increase (Decrease) From Income (Loss) On Investment, Including Interest On Participant Loans Subsequent Events EBP, Subsequent Event [Policy Text Block] Tax Status EBP, Tax Status [Text Block] Maximum aggregate equal percentage EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Document Information [Table] Document Information [Table] Notes Receivable from Participants EBP, Note Receivable from Participant [Policy Text Block] Range Of Participants [Domain] Range Of Participants [Domain] Range Of Participants [Domain] EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution [Abstract] Net assets available for benefits Net assets available for benefits, beginning of year Net assets available for benefits, end of year EBP, Net Asset Available for Benefit Entity [Domain] Entity [Domain] Available eligible earnings, percentage EBP, Employer Contribution, Matching Percentage Fair Value Measured at Net Asset Value Per Share Fair Value Measured at Net Asset Value Per Share [Member] EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items]