Variable Interest Entities - Net Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 340	$ 218
Great Valley Solar
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	278	284
Other assets	40	39
Total assets	318	323
Other liabilities	14	13
Total liabilities	14	13
Accumulated depreciation	24	18
Great Valley Solar | Tax Equity Investors
Variable Interest Entity [Line Items]
Noncontrolling interest	88	82
Copper Mountain - Mesquite Solar
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	435	446
Other assets	174	176
Total assets	609	622
Other liabilities	79	71
Total liabilities	79	71
Accumulated depreciation	40	30
Copper Mountain - Mesquite Solar | Tax Equity Investors
Variable Interest Entity [Line Items]
Noncontrolling interest	122	$ 134
CED Nevada Virginia
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	647
Other assets	57
Total assets	704
Other liabilities	328
Total liabilities	328
Noncontrolling interest	128
Accumulated depreciation	$ 5