v3.26.3
Subsequent Event (Narrative) (Details) - USD ($)
$ in Millions
9 Months Ended
Oct. 28, 2025
Sep. 30, 2026
Sep. 30, 2025
Subsequent Event [Line Items]      
Payment to renewable generation asset developer   $ 0.0 $ 1,091.7
Business Combination, Price of Acquisition, Expected $ 35.2    
NIPSCO Holdings II      
Subsequent Event [Line Items]      
Subsidiary, Ownership Percentage, Parent 19.90%