Business Segments, Consolidated Revenues and Expenses (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Consolidated Revenues [Abstract]
Total consolidated revenues		$ 8,467.5	$ 6,607.6	$ 17,766.0	$ 13,928.0
Operating costs and expenses:
Cost of sales	[1]	6,391.9	4,731.1	13,532.3	10,066.8
Other operating costs and expenses	[2]	719.8	605.6	1,407.4	1,216.0
Depreciation, amortization and accretion		425.3	379.2	819.6	755.4
Asset impairment and related charges		15.9	14.0	16.8	25.2
Net losses (gains) attributable to asset sales		(0.9)	0.3	(1.4)	0.0
General and administrative costs		51.4	45.7	104.4	96.1
Total consolidated costs and expenses		7,603.4	5,775.9	15,879.1	12,159.5
NGL Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues		3,273.7	2,620.6	6,687.0	5,966.4
Crude Oil Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues		2,781.2	1,899.6	6,352.1	3,706.8
Natural Gas Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues		792.8	786.2	1,597.6	1,547.4
Petrochemical & Refined Products Services [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues		$ 1,619.8	$ 1,301.2	$ 3,129.3	$ 2,707.4

[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.

[2] Represents the cost of operating our plants, pipelines and other fixed assets excluding: depreciation, amortization and accretion charges; asset impairment and related charges; and net losses (or gains) attributable to asset sales.