Segment And Geographic Information (Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Income from operations for reportable segments	$ 365	$ 366	$ 266	$ 236	$ 153	$ 46	$ 180	$ 202	$ 1,233	$ 581	$ 960
Interest expense									(159)	(79)	(35)
Other income, net									7	56	38
Income before income taxes									$ 1,081	$ 558	$ 963