Inventories (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Available-for-Sale Inventory by Product Type [Abstract]
NGLs	$ 594.3		$ 563.6
Petrochemicals and refined products	304.5		443.4
Crude oil	119.4		39.2
Natural gas	70.2		65.5
Total	1,088.4		1,111.7
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	36,015.5	[1]	38,292.6	[1]	28,723.1	[1]
Lower of cost or market adjustments	$ 22.1		$ 9.5		$ 7.9

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