Variable Interest Entities - Net Assets (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 249	$ 218
Great Valley Solar
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	282	284
Other assets	40	39
Total assets	322	323
Term Loan	0	0
Other liabilities	13	13
Total liabilities	13	13
Accumulated depreciation	20	18
Great Valley Solar | Tax Equity Investors
Variable Interest Entity [Line Items]
Noncontrolling interest	85	82
Copper Mountain - Mesquite Solar
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	442	446
Other assets	174	176
Total assets	616	622
Term Loan	0	0
Other liabilities	73	71
Total liabilities	73	71
Accumulated depreciation	33	30
Copper Mountain - Mesquite Solar | Tax Equity Investors
Variable Interest Entity [Line Items]
Noncontrolling interest	130	$ 134
CED Nevada Virginia
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	583
Other assets	45
Total assets	628
Term Loan	466
Other liabilities	81
Total liabilities	547
Noncontrolling interest	$ 33