Long-Term Debt and Short-Term Borrowings - Post-Swap Borrowing, Long-Term Debt, Including Current Portion (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Long-Term Debt
Total long-term debt	$ 19,359	$ 14,156
Fixed-rate debt
Long-Term Debt
Interest rate - effective	3.01%	2.67%
Total long-term debt	$ 17,061	$ 11,249
Floating-rate debt
Long-Term Debt
Interest rate - effective	1.06%	1.44%
Total long-term debt	$ 2,298	$ 2,907