Equity Investment (Summary of Investment in Joint Venture, Income Statement Data) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Net sales	$ 203.2	$ 272.0	$ 451.9	$ 514.1
Gross profit	67.8	103.4	159.1	194.8
Net earnings	50.3	54.5	(175.9)	93.6
WAVE [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	75.3	105.5	170.7	202.4
Gross profit	41.4	58.9	96.3	111.5
Net earnings	$ 29.1	$ 43.2	$ 69.9	$ 83.4