v3.25.4
Short-Term Borrowings (Narrative) (Details)
$ in Millions
12 Months Ended
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Jun. 27, 2025
USD ($)
Mar. 14, 2024
USD ($)
Short-term Debt [Line Items]          
Revolving credit facility, maximum   $ 1,850.0 $ 1,500.0    
Line of Credit Facility, Amount Outstanding $ 0.0 0.0      
Commercial paper outstanding 736.0 604.6      
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount 0.0        
Cash from financing activities 0.0 (337.6)      
Accounts receivable securitization fees 1.4 1.5 $ 2.7    
Senior Notes $ 13,253.0 12,103.0      
NiSource          
Short-term Debt [Line Items]          
Senior Notes       $ 900.0  
5.35% Notes Due 2034 | NiSource          
Short-term Debt [Line Items]          
Debt, Weighted Average Interest Rate 5.35%       5.35%
Senior Notes $ 650.0 650.0     $ 650.0
Accounts Receivable Program          
Short-term Debt [Line Items]          
Seasonal Limit $ 175.0        
Number of Agreements 3        
Commercial Paper          
Short-term Debt [Line Items]          
Revolving credit facility, maximum $ 2,500.0 $ 1,850.0      
Short-term Debt, Weighted Average Interest Rate, at Point in Time 3.92% 4.73%