Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 56.9	$ 28.1	$ 163.7	$ 136.5
Average basic shares outstanding	58.1	59.0	58.0	58.8
Effect of dilutive stock options	0.7	0.9	0.8	1.0
Average diluted shares outstanding	58.8	59.9	58.8	59.7
Earnings per share - basic:
Net income attributable to common shareholders	$ 0.98	$ 0.48	$ 2.82	$ 2.32
Earnings per share - diluted:
Net income attributable to common shareholders	$ 0.97	$ 0.47	$ 2.78	$ 2.28