Equity Method Investments (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments	$ 78.7	$ 58.0	$ 112.8
Clean energy investments
Schedule of Equity Method Investments [Line Items]
Number of equity method investments	3
Impairment of Equity Method Investments		47.0
Reduction in Equity Method Investment Long-Term Obligation		89.0
Loss from equity method investments		$ 42.0