Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Net Income Per Common Share
Net income available to common shareholders	$ 120.9	$ 80.0	$ 233.1	$ 169.6
Weighted average number of common shares outstanding	88.5	89.1	88.4	89.3
Dilutive shares (additional common shares issuable under stock-based awards)	1.4	1.6	1.6	1.6
Weighted average number of common shares outstanding, assuming dilution	89.9	90.7	90.0	90.9
Net income per common share (in dollars per share)	$ 1.37	$ 0.90	$ 2.64	$ 1.90
Net income per common share, assuming dilution (in dollars per share)	$ 1.34	$ 0.88	$ 2.59	$ 1.87
Stock-based compensation awards excluded from the computation of net income per common share, assuming dilution	0.1	0.1	0.1	0.2