Fair Value Measurements (Assets and Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs (Level 3)) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due in one year or less	$ 44	$ 51
Due after one year through three years	44	32
Fair Value, Inputs, Level 2 | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency exchange forward contracts	14	0
Fair Value, Inputs, Level 2 | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency exchange forward contracts	$ 20	$ 20