Net Income per Common Share (Tables)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Summary of Earnings Per Share Basic and Diluted

	Quarter Ended September 30,				Nine Months Ended September 30,
(In millions, except per share data)	2018		2017		2018		2017
Basic net income per common share:
Net income	$	80.1	$	69.7	$	210.5	$	195.9
Weighted average common shares outstanding		87.0		90.1		88.6		90.7
Basic net income per common share	$	0.92	$	0.77	$	2.37	$	2.16
Diluted net income per common share:
Net income		80.1		69.7		210.5		195.9
Weighted average common shares outstanding — Basic		87.0		90.1		88.6		90.7
Plus incremental shares from assumed conversions:
Restricted stock units		0.5		0.4		0.4		0.4
Stock options		0.6		0.9		0.7		1.0
Weighted average common shares outstanding — Dilutive		88.1		91.4		89.7		92.1
Diluted net income per common share	$	0.91	$	0.76	$	2.35	$	2.13