Variable Interest Entities - Net Assets (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 216	$ 191
Great Valley Solar
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	288	293
Other assets	45	40
Total assets	333	333
Other liabilities	15	17
Total liabilities	15	17
Accumulated depreciation	13	9
Great Valley Solar | Tax Equity Investors
Variable Interest Entity [Line Items]
Noncontrolling interest	73	62
Copper Mountain - Mesquite Solar
Variable Interest Entity [Line Items]
Non-utility property, less accumulated depreciation	453	461
Other assets	189	128
Total assets	642	589
Other liabilities	69	18
Total liabilities	69	18
Accumulated depreciation	23	15
Copper Mountain - Mesquite Solar | Tax Equity Investors
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 140	$ 126