Long-Term Debt and Short-Term Borrowings - Short-Term Borrowings and Current Portion of Long-Term Debt (Details) - USD ($) $ in Millions |
Jun. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Short-Term Borrowings and Current Portion of Long-Term Debt | ||
| Short-term borrowings and current portion of long-term debt | $ 3,225 | $ 1,853 |
| Commercial paper | ||
| Short-Term Borrowings and Current Portion of Long-Term Debt | ||
| Short-term borrowings and current portion of long-term debt | $ 1,500 | $ 745 |