Investments in Affiliated Companies (Future Debt Maturities) (Details 8) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
2016	$ 336.6
2017	550.0
2018	350.0
2019	566.0
2020	250.0
Thereafter	2,360.0
Total debt principal	$ 4,412.6	$ 4,286.2
RRPF Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Long-term Debt, Contingent Payment of Principal or Interest	320.5
2016	$ 389.4
2017	81.3
2018	494.7
2019	584.4
2020	310.0
Thereafter	894.0
Total debt principal	$ 2,753.8

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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