Long-Term Debt and Short-Term Borrowings - Short-Term Borrowings and Current Portion of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Long-Term Debt
Total long-term debt	$ 14,156	$ 13,198
Short-Term Borrowings and Current Portion of Long-Term Debt
Short-term borrowings and current portion of long-term debt	$ 1,211	1,853
Current portion of long-term debt
Long-Term Debt
Interest rate - effective	1.85%
Total long-term debt	$ 745	1,102
Commercial paper
Long-Term Debt
Interest rate - effective	2.33%
Short-Term Borrowings and Current Portion of Long-Term Debt
Short-term borrowings and current portion of long-term debt	$ 435	745
Other borrowings
Long-Term Debt
Interest rate - effective	5.95%
Short-Term Borrowings and Current Portion of Long-Term Debt
Short-term borrowings and current portion of long-term debt	$ 31	$ 6