Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock Capital Stock, Class A common stock	Common Stock Capital Stock, Class B common stock	Treasury Stock Treasury Stock, Class A common stock	Treasury Stock Treasury Stock, Class B common stock	Paid-in Capital	Earnings Invested in the Business	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2017		$ 36.6	$ 3.5	$ (34.6)	$ (0.6)	$ 32.2	$ 983.6	$ 130.8
Increase (Decrease) in Stockholders' Equity
Net issuance of stock awards				7.8	0.0	(8.8)
Net earnings	$ 13.7						13.7
Dividends							(5.9)
Other comprehensive income (loss), net of tax	(0.8)							(0.8)
Ending balance at Jul. 01, 2018	1,160.9	36.6	3.5	(26.8)	(0.6)	23.4	1,134.8	(10.0)
Beginning balance at Apr. 01, 2018		36.6	3.5	(27.3)	(0.6)	21.1	1,153.2	4.8
Increase (Decrease) in Stockholders' Equity
Net issuance of stock awards				0.5	0.0	2.3
Net earnings	(15.4)						(15.4)
Dividends							(3.0)
Other comprehensive income (loss), net of tax	(14.8)							(14.8)
Ending balance at Jul. 01, 2018	1,160.9	36.6	3.5	(26.8)	(0.6)	23.4	1,134.8	(10.0)
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment | Accounting Standards Update 2016-01							140.0	(140.0)
Cumulative effect adjustment | Accounting Standards Update 2014-09							3.4
Beginning balance at Dec. 30, 2018	1,159.5	36.6	3.5	(25.4)	(0.6)	24.4	1,138.1	(17.1)
Increase (Decrease) in Stockholders' Equity
Net issuance of stock awards				4.5	0.0	(1.2)
Net earnings	105.9						105.9
Dividends							(5.9)
Other comprehensive income (loss), net of tax	5.4							5.4
Ending balance at Jun. 30, 2019	1,268.2	36.6	3.5	(20.9)	(0.6)	23.2	1,238.1	(11.7)
Beginning balance at Mar. 31, 2019		36.6	3.5	(21.3)	(0.6)	21.0	1,157.2	(18.6)
Increase (Decrease) in Stockholders' Equity
Net issuance of stock awards				0.4	0.0	2.2
Net earnings	83.8						83.8
Dividends							(2.9)
Other comprehensive income (loss), net of tax	6.9							6.9
Ending balance at Jun. 30, 2019	$ 1,268.2	$ 36.6	$ 3.5	$ (20.9)	$ (0.6)	$ 23.2	$ 1,238.1	$ (11.7)