Financial Instruments - Cumulative Basis Adjustments for Fair Value Hedges (Details) - USD ($) $ in Millions |
Sep. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Short-term debt | ||
| Amounts recorded in the Consolidated Statement of Financial Position related to cumulative basis adjustments for fair value hedges | ||
| Carrying amount of the hedged item | $ (326) | $ (1,878) |
| Cumulative hedging adjustment included in the carrying amount - assets/(liabilities) | (1) | (4) |
| Hedging adjustments on discontinued hedging relationships | (1) | (6) |
| Long-term debt | ||
| Amounts recorded in the Consolidated Statement of Financial Position related to cumulative basis adjustments for fair value hedges | ||
| Carrying amount of the hedged item | (4,834) | (6,004) |
| Cumulative hedging adjustment included in the carrying amount - assets/(liabilities) | (469) | (333) |
| Hedging adjustments on discontinued hedging relationships | $ (378) | $ (213) |