Short-Term and Long-Term Borrowings (Short-Term Borrowings) (Narrative) (Details) - USD ($) $ in Millions	48 Months Ended
	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Unused bank credit lines		$ 7,900	$ 4,900
Outstanding letters of credit		$ 188	$ 203
Weighted-average interest rate		2.20%	4.10%
Fair Value, Inputs, Level 2 [Member]
Short-term Debt [Line Items]
Fair value of short-term borrowings		$ 430	$ 1,190
Scenario, Forecast [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Description	2 years