Stock-Based Compensation (Schedule Of Option Activity And Changes) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Options
Options, Outstanding, beginning balance | shares	1,404,734
Options, Granted | shares	289,553
Options, Exercised | shares	(401,505)
Options, Cancelled | shares	(23,181)
Options, Outstanding, ending balance | shares	1,269,601
Options, Exercisable, ending balance | shares	719,676
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding, beginning balance (in dollars per share) | $ / shares	$ 33.76
Weighted Average Exercise Price, Granted (in dollars per share) | $ / shares	61.87
Weighted Average Exercise Price, Exercised (in dollars per share) | $ / shares	29.68
Weighted Average Exercise Price, Cancelled (in dollars per share) | $ / shares	56.92
Weighted Average Exercise Price, Outstanding, ending balance (in dollars per share) | $ / shares	41.04
Weighted Average Exercise Price, Exercisable, ending balance (in dollars per share) | $ / shares	$ 28.89
Weighted Average Remaining Term (Years), Outstanding	5 years 10 months 24 days
Weighted Average Remaining Term (Years), Exercisable	3 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding | $	$ 83
Aggregate Intrinsic Value, Exercisable | $	$ 56