Variable Interest Entities (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($) MW	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Variable Interest Entity [Line Items]
Proceeds from the sale of membership interests in VIEs	$ 44	$ 0
Securitization bonds
Variable Interest Entity [Line Items]
Total principal amount outstanding	659		$ 700
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Regulatory asset	638		666
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investments	$ 66		$ 64
Variable Interest Entity, Not Primary Beneficiary | T.E.S. Filer City
Variable Interest Entity [Line Items]
Ownership interest	50.00%
Variable Interest Entity, Not Primary Beneficiary | Grayling
Variable Interest Entity [Line Items]
Ownership interest	50.00%
Variable Interest Entity, Not Primary Beneficiary | Genesee
Variable Interest Entity [Line Items]
Ownership interest	50.00%
Variable Interest Entity, Not Primary Beneficiary | Craven
Variable Interest Entity [Line Items]
Ownership interest	50.00%
NWO Wind Equity Holdings
Variable Interest Entity [Line Items]
Proceeds from the sale of membership interests in VIEs	$ 36
NWO Wind Equity Holdings | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Ownership interest	50.00%
NWO Holdco | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Nameplate capacity (in MW) | MW	100
Delta Township, Michigan, Solar Project
Variable Interest Entity [Line Items]
Proceeds from the sale of membership interests in VIEs	$ 8
Delta Township, Michigan, Solar Project | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Ownership interest	50.00%
Nameplate capacity (in MW) | MW	24