Derivative Financial Instruments And Hedging Activities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Average maturity of foreign currency forward contracts, in years	1 year
Cash and equivalents	$ 902	$ 963
Marketable securities held in trust	207
Derivative notional amount	$ 5,000	$ 5,800
Maximum
Derivative Instruments, Gain (Loss) [Line Items]
Maturity of fixed-income securities, in years	5 years