Inventories (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Available-for-Sale Inventory by Product Type [Abstract]
NGLs		$ 639.9	$ 579.1
Petrochemicals and refined products		148.0	295.6
Crude oil		222.1	97.8
Natural gas		28.1	41.7
Total		1,038.1	1,014.2
Summary of cost of sales and lower of cost or market adjustments [Abstract]
Cost of sales	[1]	19,612.9	40,464.1	$ 40,770.2
Lower of cost or market adjustments within cost of sales		$ 19.8	$ 22.8	$ 18.5

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