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Variable Interest Entities - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) MW	Sep. 30, 2019
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 191	$ 113
Texas Solar 4 \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Generating capacity (MW AC) \| MW		40
Texas Solar 4 \| Variable Interest Entity, Primary Beneficiary \| Con Edison Development
Variable Interest Entity [Line Items]
Percentage of variable interests (less than)		80.00%
Ownership percentage acquired			20.00%
Tax Equity Projects \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Income (loss)	(64)
Income (loss), after tax	$ (48)
Tax Equity Projects \| Variable Interest Entity, Primary Beneficiary \| Con Edison Development
Variable Interest Entity [Line Items]
Percentage of variable interests (less than)	100.00%
Tax Equity Projects \| Variable Interest Entity, Primary Beneficiary \| Tax Equity Investors
Variable Interest Entity [Line Items]
Income (loss)	$ 98
Income (loss), after tax	$ 74