Earnings per Share and Stock Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		49 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018	Aug. 31, 2019	Feb. 06, 2019	Jul. 27, 2015
Net (loss) income
Net income	$ 32.3	$ 31.5	$ 99.7	$ 95.7
Shares
Shares (in shares)	34,000,000.0	34,300,000	34,100,000	34,300,000
Per Share Amount
Net income (in dollars per share)	$ 0.95	$ 0.92	$ 2.92	$ 2.79
Dilutive securities, principally common stock options
Common stock equivalents (in shares)	200,000	100,000	100,000	100,000
Common stock equivalents (in dollars per share)	$ (0.01)		$ (0.01)	$ (0.01)
Net (loss) income
Net income	$ 32.3	$ 31.5	$ 99.7	$ 95.7
Weighted average number of shares:
Shares (in shares)	34,200,000	34,400,000	34,200,000	34,400,000
Securities not included in the computation of diluted EPS
Net income (in dollars per share)	$ 0.94	$ 0.92	$ 2.91	$ 2.78
Dilutive securities, principally common stock options
Options to purchase shares of Class A common stock, anti-dilutive	0		0
Shares repurchased
Number of shares repurchased	47,943	57,156	178,340	195,790
Cost of shares repurchased	$ 4.5	$ 4.7	$ 14.8	$ 15.5
July 27, 2015
Shares repurchased
Number of shares repurchased	15,907	57,156	146,304	195,790
Cost of shares repurchased	$ 1.5	$ 4.7	$ 11.8	$ 15.5
July 27, 2015 | Class A
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased							$ 100.0
Cost of shares repurchased					$ 100.0
February 6, 2019
Shares repurchased
Number of shares repurchased	32,036		32,036
Cost of shares repurchased	$ 3.0		$ 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	$ 147.0		$ 147.0