Earnings per Share and Stock Repurchase Program (Details) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2020 USD ($) item $ / shares shares	Jun. 30, 2019 USD ($) item $ / shares shares	Jun. 28, 2020 USD ($) item $ / shares shares	Jun. 30, 2019 USD ($) item $ / shares shares	Feb. 06, 2019 USD ($)	Jul. 31, 2015 USD ($) item	Jul. 27, 2015 USD ($)
Net (loss) income
Net income	$ 20.2	$ 36.4	$ 52.2	$ 67.4
Shares
Shares (in shares) | shares	33,800,000	34,100,000	33,900,000	34,100,000
Per Share Amount
Net income (in dollars per share) | $ / shares	$ 0.60	$ 1.06	$ 1.54	$ 1.97
Dilutive securities, principally common stock options
Common stock equivalents (in shares) | shares	200,000	100,000	100,000	100,000
Common stock equivalents (in dollars per share) | $ / shares	$ (0.01)		$ (0.01)
Net (loss) income
Net income	$ 20.2	$ 36.4	$ 52.2	$ 67.4
Weighted average number of shares:
Shares (in shares) | shares	34,000,000.0	34,200,000	34,000,000.0	34,200,000
Securities not included in the computation of diluted EPS
Net income (in dollars per share) | $ / shares	$ 0.59	$ 1.06	$ 1.53	$ 1.97
Dilutive securities, principally common stock options
Options to purchase shares of Class A common stock, anti-dilutive | shares	0	0
Shares repurchased
Number of shares repurchased | shares	78,828	55,988	253,535	130,397
Cost of shares repurchased	$ 6.4	$ 4.7	$ 21.1	$ 10.3
Number of stock repurchase programs | item	2	2	2	2		2
July 27, 2015
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased							$ 100.0
Number of shares repurchased | shares		55,988		130,397
Cost of shares repurchased		$ 4.7		$ 10.3
July 27, 2015 | Class A
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased						$ 150.0	$ 100.0
February 6, 2019
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased					$ 150.0
Number of shares repurchased | shares	78,828		253,535
Cost of shares repurchased	$ 6.4		$ 21.1
February 6, 2019 | Class A
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased					$ 150.0
Remaining authorized repurchase amount	$ 121.3		$ 121.3