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Impairments (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
Impairments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Impairment losses of cost investments and intangible assets				$ 7
Petra Nova
Schedule of Equity Method Investments [Line Items]
Impairment losses		$ 18	$ 101
Letters of credit issued			12	12
Investment in cash			95
Guarantor obligations (up to)			$ 124	$ 124
West/Other \| Disposal Group, Held-for-sale, Not Discontinued Operations \| Home Solar
Schedule of Equity Method Investments [Line Items]
Adjustment to carrying amount of assets and liabilities	$ 29
Other noncurrent assets- held for sale	88
Non-current liabilities - held-for-sale	$ 44