Investment in Unconsolidated Affiliates Summarized Income Statement of Equity Method Investment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]
Operating revenues	$ 646.0	$ 803.0	$ 1,852.0	$ 2,632.0
Cost of sales	287.0	439.0	856.0	1,550.0
Operating income	(975.0)	152.0	(778.0)	452.0
Net income	$ (985.0)	$ 139.0	$ (817.0)	$ 408.0