Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Available-for-Sale Inventory by Product Type [Abstract]
NGLs	$ 702.5				$ 702.5				$ 563.6
Petrochemicals and refined products	246.9				246.9				443.4
Crude oil	57.5				57.5				39.2
Natural gas	62.3				62.3				65.5
Total	1,069.2				1,069.2				1,111.7
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	8,794.0	[1]	9,787.6	[1]	26,655.0	[1]	28,397.2	[1]
Lower of cost or market adjustments	$ 2.2		$ 5.1		$ 16.1		$ 6.8

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