Equity Investment (Summary of Investment in Joint Venture, Income Statement Data) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Net sales	$ 246.3	$ 277.1	$ 698.2	$ 791.2
Gross profit	91.2	111.7	250.3	306.5
Net earnings	54.0	73.2	(121.9)	166.8
WAVE [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	86.3	99.9	257.0	302.3
Gross profit	49.4	56.9	145.7	168.4
Net earnings	$ 33.4	$ 43.9	$ 103.3	$ 127.3