Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2017

Earnings Per Share [Abstract]

Computation of Basic and Diluted Earnings per Share

	Three Months Ended
	March 31,
(in millions, except per share data)	2017		2016
Net income attributable to common shareholders	$	63.1	$	55.0
Average basic shares outstanding	59.3		58.2
Effect of dilutive stock options	1.0		0.7
Average diluted shares outstanding	60.3		58.9
Earnings per basic share	$	1.06	$	0.95
Earnings per diluted share	$	1.05	$	0.93