Divestitures (Details) $ in Millions |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
|
Sep. 30, 2019
USD ($)
|
Sep. 30, 2018
USD ($)
|
Mar. 31, 2018
USD ($)
|
Sep. 30, 2019
USD ($)
|
Sep. 30, 2018
USD ($)
|
Jul. 10, 2019
MW
|
|
| Business Acquisition [Line Items] | ||||||
| Dividends paid(2) | $ (401) | $ (20) | ||||
| Impairment losses | 0 | $ 0 | $ 55 | $ 0 | ||
| Garrison Energy Center and RockGen Energy LLC [Member] | ||||||
| Business Acquisition [Line Items] | ||||||
| Ownership percentage of acquiree | 100.00% | |||||
| Proceeds from Sale of Productive Assets | 360 | |||||
| Garrison Energy Center LLC [Member] | ||||||
| Business Acquisition [Line Items] | ||||||
| Power generation capacity | MW | 309 | |||||
| RockGen Energy LLC [Member] | ||||||
| Business Acquisition [Line Items] | ||||||
| Power generation capacity | MW | 503 | |||||
| Dividend Paid [Member] | ||||||
| Business Acquisition [Line Items] | ||||||
| Dividends paid(2) | $ 400 | |||||
| Commodity Contract [Member] | ||||||
| Business Acquisition [Line Items] | ||||||
| Proceeds from Hedge, Financing Activities | $ 52 | |||||