Investments in Affiliated Companies (Balance Sheet, Affiliates) (Details 5) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Summarized balance sheet for all affiliated companies
Current assets	$ 144.8	$ 254.1
Noncurrent assets	3,847.2	3,363.6
Total assets	3,992.0	3,617.7
Current liabilities	446.8	551.0
Noncurrent liabilities	2,704.9	2,341.4
Shareholders’ equity	840.3	725.3
Total liabilities and shareholders' equity	$ 3,992.0	$ 3,617.7