Investments in Affiliates - Financial Information for Equity Method Investments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
ASSETS
Current assets	$ 52.7		$ 43.5
Non-current assets	935.6		673.2
Total assets	988.3		716.7
Liabilities [Abstract]
Current liabilities	53.0		44.2
Non-current liabilities	245.9		107.9
Total liabilities	298.9		152.1
Income Statement [Abstract]
Operating revenue	71.0		37.8		29.8
Operating costs and expenses	65.9		31.1		32.5
Operating (loss) income	5.1		6.7		(2.7)
Income (loss) from continuing operations	5.0	[1]	6.8	[1]	(11.5)	[1]
Net income (loss)	$ 5.0		$ 6.8		$ (11.5)

[1] Includes earnings from equity method investments held by the investee.