Derivative Instruments and Hedging Activities(Schedule of Terminated Cash Flows) (Details) - Accumulated Net Gain (Loss) from Derivative Instruments Designated as Cash Flow Hedges [Member] - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|---|
| Accumulated Other Comprehensive Income (Loss) [Line Items] | |||
| Accumulated Other Comprehensive Income related to discontinued cash flow hedges, before tax | $ 121 | $ 78 | $ 68 |
| Other Comprehensive Income (loss), Unrealized Gain (loss) on terminated cash flow hedges arising during the period, before tax | 55 | 23 | |
| Other Comprehensive Income (loss), Reclassification Adjustment from AOCI on terminated cash flow hedges, before tax | $ (12) | $ (13) |