Stock-Based Incentive Compensation Plans (Compensation Expense By Award Type) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee service share-based compensation, aggregate disclosures [Abstract]
Compensation expense	$ 48	$ 47	$ 44
Recognized tax benefit	10	16	15
Stock options [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Compensation expense	5	9	9
Performance Shares [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Compensation expense	14	12	10
SARs [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Compensation expense	(1)	2	3
Restricted Stock Units And Non-Vested Stock [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Compensation expense	$ 30	$ 24	$ 22