DERIVATIVES - Cumulative Basis Adjustments for Fair Value Hedges (Details) - Fair Value Hedging - USD ($) $ in Millions |
Jun. 30, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Securities due within one year | ||
| Derivative [Line Items] | ||
| Carrying Amount of the Hedged Item | $ 0 | $ (599) |
| Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item | 0 | 0 |
| Long-term debt | ||
| Derivative [Line Items] | ||
| Carrying Amount of the Hedged Item | (1,517) | (1,494) |
| Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item | $ (20) | $ 3 |