Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2012
Available-for-Sale Inventory by Product Type [Abstract]
NGLs	$ 531.4				$ 594.3
Petrochemicals and refined products	443.3				304.5
Crude oil	165.6				119.4
Natural gas	18.8				70.2
Total	1,159.1				1,088.4
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	9,692.5	[1]	9,665.8	[1]
Lower of cost or market adjustments	$ 2.7		$ 5.9

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