Share-Based Compensation Plans (Schedule Of Changes In Stock Options) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Option shares outstanding, December 31, 2016, Number of shares | shares	1,350,600
Option shares exercised, Number of shares | shares	(78,200)
Option shares outstanding, December 31, 2017, Number of shares | shares	1,272,400
Option shares exercisable, vested and expected to vest, December 31, 2017, Number of shares | shares	1,272,400
Option shares outstanding, December 31, 2016, Weighted-average exercise price | $ / shares	$ 34.66
Option shares exercised, Weighted-average exercise price | $ / shares	(41.62)
Option shares outstanding, December 31, 2017, Weighted-average exercise price | $ / shares	34.23
Option shares exercisable, vested and expected to vest, December 31, 2017. Weighted-average exercise price | $ / shares	$ 34.23
Option shares outstanding, December 31, 2017, Weighted-average remaining contractual term	3 years 4 months 24 days
Option shares exercisable, vested and expected to vest, December 31, 2017. Weighted-average remaining contractual term	3 years 4 months 24 days
Option shares outstanding, December 31, 2017, Aggregate intrinsic value | $	$ 33.5
Option shares exercisable, vested and expected to vest, December 31, 2017, Aggregate intrinsic value | $	$ 33.5