Variable Interest Entities (Schedule of VIE Information) (Details) $ in Millions	1 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2026 USD ($) MW	Sep. 30, 2026 USD ($) MW	Sep. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)
Variable Interest Entity [Line Items]
Deemed contribution from sale of membership interest		$ 166	$ 0
BG Solar Holdings
Variable Interest Entity [Line Items]
Deemed contribution from sale of membership interest				$ 35
Class A - Tax Equity Membership
Variable Interest Entity [Line Items]
Proceeds from the sale of membership interests in VIEs	$ 56	76	$ 0	$ 15
Deemed contribution from sale of membership interest		$ 87
Variable Interest Entity, Primary Beneficiary \| BG Solar Holdings
Variable Interest Entity [Line Items]
Nameplate capacity (in MW) \| MW		200
Variable Interest Entity, Primary Beneficiary \| HL Solar Holdings
Variable Interest Entity [Line Items]
Proceeds from the sale of membership interests in VIEs		$ 24
Deemed contribution from sale of membership interest		$ 166
Variable Interest Entity, Primary Beneficiary \| HL Solar Holdings \| St. Clair County
Variable Interest Entity [Line Items]
Nameplate capacity (in MW) \| MW	100
Variable Interest Entity, Primary Beneficiary \| HL Solar Holdings \| Hart Township
Variable Interest Entity [Line Items]
Nameplate capacity (in MW) \| MW	120