Derivative Financial Instruments (Location And Amounts Of Pre-Tax Gains (Losses) On Derivative Financial Instruments Not Designated As Hedges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward Contracts [Member] | Foreign Currency Gain (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of net gains (losses) on derivative instruments	$ (3)	$ 0