Equity Method Investments (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments	$ 10.4	$ 12.6	$ 43.6	$ 58.6
Equity method investments summarized financial data basis			100.00%
Equity Method Investment, Other than Temporary Impairment				39.0
Equity Method Investments, Reduction In Long-Term Obligations		$ 40.0
Equity Method Investments Net Gain (Loss) From Impairment and Reduction In Obligations			$ 7.0	$ 1.0
Clean energy investments
Schedule of Equity Method Investments [Line Items]
Number of equity method investments	3		3