Equity Investment (Summary of Investment in Joint Venture, Balance Sheet Data) (Details) - WAVE [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Current assets	$ 105.4	$ 112.9
Current assets of discontinued operations		33.8
Nonncurrent assets	34.3	34.9
Current liabilities	23.7	113.6
Current liabilities of discontinued operations		6.9
Other noncurrent liabilities	$ 284.3	$ 293.6