Fair Value Measurements (Unrealized Gains (Losses) Recognized On Equity Securities Still Held at The Reporting Date) (Details) - Equity Securities [Member] - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2020 |
Sep. 30, 2019 |
Sep. 30, 2020 |
Sep. 30, 2019 |
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||||
| Unrealized gains (losses) | $ 223 | $ 21 | $ 65 | $ 500 |
| FPL [Member] | ||||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||||
| Unrealized gains (losses) | $ 129 | $ 18 | $ 50 | $ 327 |