Equity Investments (Summary of Investment in Joint Venture, Income Statement Data) (Details) - WAVE [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Net sales	$ 344.5	$ 330.7	$ 309.7
Gross profit	192.7	192.4	172.1
Net earnings	$ 144.3	$ 151.9	$ 136.5