Variable Interest Entities - Net Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Noncontrolling interest	$ 191	$ 113
Great Valley Solar
Business Acquisition [Line Items]
Restricted cash	0	0
Non-utility property, less accumulated depreciation	293	313
Other assets	40	18
Total assets	333	331
Long-term debt due within one year	0	0
Other liabilities	17	17
Long-term debt	0	0
Total liabilities	17	17
Accumulated depreciation	9	1
Copper Mountain Solar - Mesquite Solar
Business Acquisition [Line Items]
Restricted cash	0	0
Non-utility property, less accumulated depreciation	461	492
Other assets	128	97
Total assets	589	589
Long-term debt due within one year	0	0
Other liabilities	18	33
Long-term debt	0	0
Total liabilities	18	33
Accumulated depreciation	15	1
Texas Solar 4
Business Acquisition [Line Items]
Restricted cash		4
Non-utility property, less accumulated depreciation		98
Other assets		9
Total assets		111
Long-term debt due within one year		2
Other liabilities		26
Long-term debt		56
Total liabilities		84
Accumulated depreciation		15
Tax Equity Investors | Great Valley Solar
Business Acquisition [Line Items]
Noncontrolling interest	62	33
Tax Equity Investors | Copper Mountain Solar - Mesquite Solar
Business Acquisition [Line Items]
Noncontrolling interest	$ 126	71
Third Party | Texas Solar 4
Business Acquisition [Line Items]
Noncontrolling interest		$ 7