Investments in Affiliated Companies (Operating Results, Affiliates) (Details 4) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Revenues	$ 304.9	$ 304.4	$ 300.5	$ 299.4	$ 300.5	$ 298.8	$ 297.5	$ 305.3	$ 1,209.2	$ 1,202.1	$ 1,175.1
Net Income	$ 17.8	$ 47.9	$ 39.3	$ 46.3	$ 56.6	$ 45.1	$ 68.0	$ 41.5	151.3	211.2	211.3
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Revenues									491.0	469.8	436.9
Gains on sales of assets									115.7	86.4	12.2
Net Income									$ 146.1	$ 161.4	$ 120.5