Inventories (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Inventory by Product Type [Abstract]
NGLs		$ 824.4		$ 824.4		$ 647.7
Petrochemicals and refined products		210.1		210.1		264.7
Crude oil		540.3		540.3		593.4
Natural gas		11.3		11.3		16.3
Total		1,586.1		1,586.1		$ 1,522.1
Summary of cost of sales and lower of cost or net realizable value adjustments [Abstract]
Cost of sales	[1]	5,609.4	$ 6,391.9	11,445.0	$ 13,532.3
Lower of cost or net realizable value adjustments recognized within cost of sales		$ 4.9	$ 0.7	$ 10.3	$ 2.6

[1] Cost of sales is a component of “Operating costs and expenses” as presented on our Unaudited Condensed 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.