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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Income from operations for reportable segments	$ 102	$ 226	$ 194	$ 134	$ 207	$ 396	$ 404	$ 401	$ 656	$ 1,408	$ 1,225
Interest expense									(124)	(126)	(159)
Other income, net									38	52	15
Income before income taxes									$ 570	$ 1,334	$ 1,081