v3.26.1
Variable Interest Entities (Narrative) (Details)
$ in Millions
1 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2026
USD ($)
MW
Dec. 31, 2025
USD ($)
Variable Interest Entity [Line Items]      
Proceeds from the sale of membership interests in VIEs $ 9    
Securitization bonds      
Variable Interest Entity [Line Items]      
Total principal amount outstanding 525 $ 525 $ 585
Variable Interest Entity, Primary Beneficiary      
Variable Interest Entity [Line Items]      
Regulatory asset 489 489 549
Variable Interest Entity, Not Primary Beneficiary      
Variable Interest Entity [Line Items]      
Investments $ 53 $ 53 $ 54
Variable Interest Entity, Not Primary Beneficiary | Craven      
Variable Interest Entity [Line Items]      
Ownership interest (in percent)   50.00%  
Variable Interest Entity, Not Primary Beneficiary | Grayling      
Variable Interest Entity [Line Items]      
Ownership interest (in percent)   50.00%  
Variable Interest Entity, Not Primary Beneficiary | Genesee      
Variable Interest Entity [Line Items]      
Ownership interest (in percent)   50.00%  
Variable Interest Entity, Not Primary Beneficiary | T.E.S. Filer City      
Variable Interest Entity [Line Items]      
Ownership interest (in percent)   50.00%  
Hart Township | Variable Interest Entity, Primary Beneficiary | HL Solar Holdings      
Variable Interest Entity [Line Items]      
Nameplate capacity (in MW) | MW   120  
St. Clair County | Variable Interest Entity, Primary Beneficiary | HL Solar Holdings      
Variable Interest Entity [Line Items]      
Nameplate capacity (in MW) | MW   96