Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Available-for-Sale Inventory by Product Type [Abstract]
NGLs	$ 490.8				$ 579.1
Petrochemicals and refined products	218.5				295.6
Crude oil	130.5				97.8
Natural gas	15.6				41.7
Total	855.4				1,014.2
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	5,678.1	[1]	11,052.7	[1]
Lower of cost or market adjustments	$ 3.5		$ 5.2

[1] Cost of sales is a component of "Operating costs and expenses" as presented on our Unaudited Condensed Statements of Consolidated Operations. Fluctuations in these amounts are primarily due to changes in energy commodity prices and sales volumes associated with our marketing activities.