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Variable Interest Entities - Additional Information (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 MW	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Variable Interest Entity [Line Items]
Noncontrolling interest		$ 218	$ 191
Texas Solar 4 \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Generating capacity (MW AC) \| MW	40
Texas Solar 4 \| Con Edison Development \| Variable Interest Entity, Primary Beneficiary
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)		$ (6)	(64)
Income (loss), after tax		$ (4)	(48)
Tax Equity Projects \| Con Edison Development \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Percentage of variable interests (less than)		100.00%
Tax Equity Projects \| Tax Equity Investors \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Income (loss)		$ 44	98
Income (loss), after tax		$ 32	$ 74