Inventories (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Available-for-Sale Inventory by Product Type [Abstract]
NGLs	$ 579.1		$ 593.8
Petrochemicals and refined products	295.6		395.1
Crude oil	97.8		42.6
Natural gas	41.7		61.6
Total	1,014.2		1,093.1
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	40,464.1	[1]	40,770.2	[1]	36,015.5	[1]
Lower of cost or market adjustments	$ 22.8		$ 18.5		$ 22.1

[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.