Earnings per Share and Stock Repurchase Program (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2020 USD ($) item $ / shares shares	Sep. 29, 2019 USD ($) item $ / shares shares	Sep. 27, 2020 USD ($) item $ / shares shares	Sep. 29, 2019 USD ($) item $ / shares shares	Feb. 06, 2019 USD ($)	Jul. 31, 2015 USD ($) item	Jul. 27, 2015 USD ($)
Net (loss) income
Net income	$ 32.9	$ 32.3	$ 85.1	$ 99.7
Shares
Shares (in shares) | shares	33,800,000	34,000,000.0	33,900,000	34,100,000
Per Share Amount
Net income (in dollars per share) | $ / shares	$ 0.97	$ 0.95	$ 2.51	$ 2.92
Dilutive securities, principally common stock options
Common stock equivalents (in shares) | shares	100,000	200,000	100,000	100,000
Common stock equivalents (in dollars per share) | $ / shares		$ (0.01)	$ (0.01)	$ (0.01)
Net (loss) income
Net income	$ 32.9	$ 32.3	$ 85.1	$ 99.7
Weighted average number of shares:
Shares (in shares) | shares	33,900,000	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	$ 0.97	$ 0.94	$ 2.50	$ 2.91
Dilutive securities, principally common stock options
Options to purchase shares of Class A common stock, anti-dilutive | shares	0	0	0	0
Shares repurchased
Number of shares repurchased | shares	41,142	47,943	294,677	178,340
Cost of shares repurchased	$ 3.7	$ 4.5	$ 24.8	$ 14.8
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		15,907		146,304
Cost of shares repurchased		$ 1.5		$ 11.8
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	41,142	32,036	294,677	32,036
Cost of shares repurchased	$ 3.7	$ 3.0	$ 24.8	$ 3.0
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	$ 117.6		$ 117.6