Business Segments, Consolidated Revenues and Expenses (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Consolidated Revenues [Abstract]
Total consolidated revenues		$ 5,920.4	$ 6,307.9	$ 16,543.5	$ 20,872.9
Operating costs and expenses:
Cost of sales	[1]	4,088.6	4,419.9	11,135.6	15,355.9
Other operating costs and expenses	[2]	612.1	642.5	1,787.2	1,834.8
Depreciation, amortization and accretion		367.1	351.1	1,085.6	1,082.0
Asset impairment charges		6.8	26.8	21.6	139.1
Loss due to Pascagoula fire		0.0	0.0	7.1	0.0
Net losses (gains) attributable to asset sales		(8.9)	12.3	(2.3)	14.7
General and administrative costs		42.0	49.0	121.0	143.2
Total consolidated costs and expenses		5,107.7	5,501.6	14,155.8	18,569.7
NGL Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Sales of NGLs and related products		1,959.0	1,844.9	5,962.9	5,936.2
Midstream services		457.9	441.9	1,373.3	1,293.0
Total consolidated revenues		2,416.9	2,286.8	7,336.2	7,229.2
Crude Oil Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Sales of crude oil		1,538.5	2,147.3	4,141.8	7,689.3
Midstream services		184.5	175.3	529.8	399.7
Total consolidated revenues		1,723.0	2,322.6	4,671.6	8,089.0
Natural Gas Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Sales of natural gas		483.7	455.0	1,104.4	1,361.2
Midstream services		230.5	254.7	695.5	767.1
Total consolidated revenues		714.2	709.7	1,799.9	2,128.3
Petrochemical & Refined Products Services [Member]
Consolidated Revenues [Abstract]
Sales of petrochemicals and refined products		871.3	780.5	2,137.9	2,764.2
Midstream services		195.0	199.5	597.9	583.4
Total consolidated revenues		1,066.3	980.0	2,735.8	3,347.6
Offshore Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Sales of crude oil		0.0	0.4	0.0	3.2
Midstream services		0.0	8.4	0.0	75.6
Total consolidated revenues		$ 0.0	$ 8.8	$ 0.0	$ 78.8

[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 charges; losses due to property damage events (e.g., the fire at our Pascagoula Facility (see Note 4)); and net losses (or gains) attributable to asset sales.