Fair Value (Narrative) (Details) - Recurring Basis [Member] - Fair Value [Member] - Level 2 [Member] - Foreign Exchange Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Summary Of Assets And Liabilities Measured At Fair Value On Recurring Basis [Line Items]
Derivative asset	$ 4
Derivative asset	1	$ 1
Derivative liabilities	$ 1	$ 1