Shareholders' Equity (Common Stock Issued With The Exercise Of Stock Options) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stockholders' Equity Note [Abstract]
Shares issued (in shares)	0.1	0.1	0.7	0.3
Proceeds from the exercise of stock options	$ 1.9	$ 4.6	$ 24.7	$ 7.8
Average exercise price per share (in dollars per share)	$ 35.27	$ 35.55	$ 33.77	$ 30.93