Stock-Based Compensation (Summary Of Changes Of Stock Options) (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding Shares, Beginning of Period | shares	1.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period | shares	(0.5)
Outstanding Shares, End of Period | shares	0.7
Outstanding, Exercisable, Ending | shares	0.7
Weighted Average Exercise Price, Outstanding, Beginning of Period | $ / shares	$ 20
Share Based Compensation Arrangement By Share Based Payment Award, Options Exercises In Period, Weighted Average Ex Price | $ / shares	21
Weighted Average Exercise Price, Outstanding, End of Period | $ / shares	20
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 20
Outstanding at period end, Aggregate Intrinsic Value Exercisable | $	$ 17.5
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $	17.5
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value | $	$ 11.3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	2 years