Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Inventory amounts by product type [Abstract]
NGLs	$ 402.7				$ 563.6
Petrochemicals and refined products	433.4				443.4
Crude oil	58.7				39.2
Natural gas	39.3				65.5
Total	934.1				1,111.7
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	9,665.8	[1]	8,819.3	[1]
Lower of cost or market adjustments	$ 5.9		$ 1.2

[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.