Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Earnings Per Share [Abstract]
Net earnings	$ 29.1	$ 12.2
Less: earnings allocated to participating securities	(0.4)	(0.2)
Net earnings available to common shareholders	$ 28.7	$ 12.0
Average shares outstanding (millions):
Basic (in shares)	38.6	38.3
Dilutive share awards (in shares)	0.3	0.4
Diluted (in shares)	38.9	38.7
Basic earnings per share on common stock (in dollars per share)	$ 0.74	$ 0.31
Diluted earnings per share on common stock (in dollars per share)	$ 0.74	$ 0.31