Equity Investment (Summary of Investment in Joint Venture, Income Statement Data) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Schedule of Equity Method Investments [Line Items]
Net sales	$ 251.9	$ 248.7
Gross profit	87.5	91.3
Net earnings	35.4	(226.2)
WAVE [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	98.6	95.4
Gross profit	58.9	54.9
Net earnings	$ 44.6	$ 40.8