v3.26.1
Schedule H, Line 4i – Schedule of Assets (Held At End of Year) (Details) - EBP 005 - USD ($)
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
EBP, Schedule of Asset Held for Investment [Line Items]    
Entity Tax Identification Number 35-2108964  
Plan Number 005  
Various plan participants $ 39,753,654  
Total Assets (Held at End of Year) $ 2,354,471,456  
Minimum    
EBP, Schedule of Asset Held for Investment [Line Items]    
Participant loan, interest rate 3.25% 3.25%
Maximum    
EBP, Schedule of Asset Held for Investment [Line Items]    
Participant loan, interest rate 10.50% 10.50%
NiSource Stock Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Cost $ 131,013,975 $ 127,200,305
Current Value 240,386,845  
Investment, Identifier [Axis]: Baird | Core Plus Bond Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 6,694,717  
Investment, Identifier [Axis]: Dodge and Cox | Stock Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 15,892,110  
Investment, Identifier [Axis]: Earnest Partners | Smid Cap Core Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 11,553,480  
Investment, Identifier [Axis]: Fidelity | Balanced Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 62,721,192  
Investment, Identifier [Axis]: Fidelity | Contrafund Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 160,762,259  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Retirement Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 3,626,113  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2010 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 5,769,913  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2015 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 5,066,652  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2020 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 25,687,078  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2025 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 50,309,799  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2030 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 142,094,490  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2035 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 123,705,194  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2040 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 173,176,951  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2045 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 137,339,911  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2050 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 174,369,363  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2055 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 122,349,053  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2060 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 53,092,305  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2065 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 15,760,339  
Investment, Identifier [Axis]: Fidelity | Freedom Blend Target Date 2070 Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 1,032,999  
Investment, Identifier [Axis]: Fidelity | Growth Company Commingled Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 326,726,877  
Investment, Identifier [Axis]: Fidelity | Money Market Government Portfolio    
EBP, Schedule of Asset Held for Investment [Line Items]    
Cost 2,393,701  
Current Value 2,393,701  
Investment, Identifier [Axis]: GQG Partners | International Equity CIT    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 51,202,986  
Investment, Identifier [Axis]: Geode Capital | Spartan Total International Index Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 21,089,863  
Investment, Identifier [Axis]: Geode Capital | Spartan Total Market Index Pool    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 234,783,134  
Investment, Identifier [Axis]: NiSource Inc. | NiSource Inc. Common Stock    
EBP, Schedule of Asset Held for Investment [Line Items]    
Cost 128,620,274  
Current Value 237,993,144  
Investment, Identifier [Axis]: PIMCO | Inflation Response Multi-Asset Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 11,394,077  
Investment, Identifier [Axis]: Vanguard | Cash Reserves Federal Money Market    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 69,805,046  
Investment, Identifier [Axis]: Vanguard | Retirement Savings Trust IV    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value 22,299,151  
Investment, Identifier [Axis]: Vanguard | Total Bond Market Index Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
Current Value $ 46,025,905