Earnings per Share and Stock Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017	Jul. 27, 2015
Net (loss) income
Net income	$ 36.0	$ 27.2	$ 64.2	$ 48.9
Shares
Shares (in shares)	34,400,000	34,500,000	34,400,000	34,500,000
Per Share Amount
Net income (in dollars per share)	$ 1.05	$ 0.79	$ 1.87	$ 1.42
Net (loss) income
Net income	$ 36.0	$ 27.2	$ 64.2	$ 48.9
Weighted average number of shares:
Shares (in shares)	34,400,000	34,500,000	34,400,000	34,500,000
Securities not included in the computation of diluted EPS
Net income (in dollars per share)	$ 1.05	$ 0.79	$ 1.87	$ 1.42
Dilutive securities, principally common stock options
Options to purchase shares of Class A common stock, anti-dilutive	0	100,000	0	100,000
Shares repurchased
Number of shares repurchased	58,579	72,674	138,634	141,786
Cost of shares repurchased	$ 4.5	$ 4.5	$ 10.8	$ 9.0
Class A
Shares repurchased
Total value of shares of the entity's Class A common stock authorized to be repurchased					$ 100.0
Remaining authorized repurchase amount	$ 27.0		$ 27.0