Inventories (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory by Product Type [Abstract]
NGLs		$ 647.7	$ 917.4
Petrochemicals and refined products		264.7	161.5
Crude oil		593.4	516.3
Natural gas		16.3	14.6
Total		1,522.1	1,609.8
Summary of cost of sales and lower of cost or net realizable value adjustments [Abstract]
Cost of sales	[1]	26,789.8	21,487.0	$ 15,710.9
Lower of cost or net realizable value adjustments recognized within cost of sales		$ 11.5	$ 9.1	$ 11.5

[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.