Accounting Policies - Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net (loss) income
Net (loss) income	$ 31.8	$ 32.3	$ 36.4	$ 31.0	$ 32.3	$ 31.5	$ 36.0	$ 28.2	$ 131.5	$ 128.0	$ 73.1
Net (loss) income									$ 131.5	$ 128.0	$ 73.1
Shares (in shares)									34.1	34.3	34.4
Dilutive securities, principally common stock options (in shares)										0.1
Shares (in shares)									34.2	34.3	34.4
Per Share Amount
Per Share Amount (in dollars per share)	$ 0.94	$ 0.95	$ 1.06	$ 0.91	$ 0.94	$ 0.92	$ 1.05	$ 0.82	$ 3.86	$ 3.73	$ 2.12
Dilutive securities, principally common stock options (in dollars per share)									(0.01)
Per Share Amount (in dollars per share)	$ 0.93	$ 0.94	$ 1.06	$ 0.91	$ 0.94	$ 0.92	$ 1.05	$ 0.82	$ 3.85	$ 3.73	$ 2.12
Shipping and Handling Costs
Cost of Goods Sold									$ 923.0	$ 908.4	$ 854.3
Research and Development Expense.
Research and Development Expense									$ 39.6	$ 34.5	$ 29.0