Variable Interest Entities (Details) $ in Millions			3 Months Ended	9 Months Ended
	Sep. 09, 2021 USD ($)	Feb. 05, 2021 wind_farm MW	Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Variable Interest Entity [Line Items]
Wind farms expected to be part of Aeolus VII | wind_farm		4
Proposed wind farm and electricity transmission project capacity (in MW) | MW		688
Equity adjustment from sale of TEFs			$ 131	$ 141	$ 312
Assets of variable interest entities (VIEs)			38,879	38,879		$ 37,823
Liabilities of variable interest entities (VIEs)			19,053	19,053		21,997
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Proceeds from sale of TEFs	$ 131
Equity adjustment from sale of TEFs	8
Noncontrolling interest in VIE	$ 139
Assets of variable interest entities (VIEs)			1,649	1,649		1,713
Liabilities of variable interest entities (VIEs)			$ 72	$ 72		$ 107