v3.26.1
Fair Value Disclosures (Details) - EBP 005 - USD ($)
Dec. 31, 2025
Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: $ 888,956,383 $ 818,674,082
Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 412,011,701 383,199,101
Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 469,954,179 429,304,449
TXNM Energy, Inc. Common Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 6,990,503 6,170,532
Level 1    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 419,002,204 389,369,633
Level 1 | Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 412,011,701 383,199,101
Level 1 | Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 0 0
Level 1 | TXNM Energy, Inc. Common Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 6,990,503 6,170,532
Level 2    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 276,644,405 241,920,269
Level 2 | Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 0 0
Level 2 | Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 276,644,405 241,920,269
Level 2 | TXNM Energy, Inc. Common Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 0 0
Fair Value, Inputs, Level 1, Level 2, and Level 3    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 695,646,609 631,289,902
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 412,011,701 383,199,101
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 276,644,405 241,920,269
Fair Value, Inputs, Level 1, Level 2, and Level 3 | TXNM Energy, Inc. Common Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: 6,990,503 6,170,532
Fair Value Measured at Net Asset Value Per Share    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value: $ 193,309,774 $ 187,384,180