Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2010
Property, plant and equipment and accumulated depreciation [Abstract]
Property, plant and equipment, gross	$ 26,408.1				$ 26,408.1				$ 23,913.4
Less accumulated depreciation	5,020.0				5,020.0				4,580.5
Property, plant and equipment , net	21,388.1				21,388.1				19,332.9
Summary of depreciation expense and capitalized interest [Abstract]
Depreciation expense	195.0	[1]	184.9	[1]	571.3	[1]	552.9	[1]
Capitalized interest	33.1	[2]	12.5	[2]	75.1	[2]	33.5	[2]
Asset Retirement Obligations [Roll Forward]
ARO liability balance, December 31, 2010					97.1
Revisions in estimated cash flows					4.7
Accretion expense					4.8
Liabilities settled during period					(3.2)
Liabilities incurred during period					0.5
ARO liability balance, September 30, 2011	103.9				103.9
Capitalized costs, asset retirement costs	38.0				38.0				34.1
Forecasted accretion expense [Abstract]
Forecast accretion expense - Remainder of 2011	1.7				1.7
Forecast accretion expense - 2012	5.3				5.3
Forecast accretion expense - 2013	5.7				5.7
Forecast accretion expense - 2014	6.1				6.1
Forecast accretion expense - 2015	5.8				5.8
Plants, pipelines and facilities [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					3	[3],[4]
Maximum estimated useful life (in years)					45	[3],[4]
Property, plant and equipment, gross	19,747.3	[4]			19,747.3	[4]			19,388.4	[4]
Underground and other storage facilities [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					5	[5],[6]
Maximum estimated useful life (in years)					40	[5],[6]
Property, plant and equipment, gross	1,556.2	[6]			1,556.2	[6]			1,477.8	[6]
Platforms and facilities [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					20	[7]
Maximum estimated useful life (in years)					31	[7]
Property, plant and equipment, gross	637.5	[7]			637.5	[7]			637.5	[7]
Transportation equipment [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					3	[8]
Maximum estimated useful life (in years)					10	[8]
Property, plant and equipment, gross	136.1	[8]			136.1	[8]			119.1	[8]
Marine vessels [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					15	[9]
Maximum estimated useful life (in years)					30	[9]
Property, plant and equipment, gross	603.7	[9]			603.7	[9]			560.0	[9]
Land [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Property, plant and equipment, gross	137.3				137.3				123.4
Construction in progress [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Property, plant and equipment, gross	3,590.0				3,590.0				1,607.2
Construction in progress [Member] | Haynesville Extension [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Property, plant and equipment, gross	$ 1,370.0				$ 1,370.0
Processing plants [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					20
Maximum estimated useful life (in years)					35
Pipelines and related equipment [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					5
Maximum estimated useful life (in years)					45
Terminal facilities [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					10
Maximum estimated useful life (in years)					35
Office furniture and equipment [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					3
Maximum estimated useful life (in years)					20
Buildings [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					20
Maximum estimated useful life (in years)					40
Laboratory and shop equipment [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					5
Maximum estimated useful life (in years)					35
Underground storage facilities [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					5
Maximum estimated useful life (in years)					35
Storage tanks [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					10
Maximum estimated useful life (in years)					40
Water wells [Member]
Property, plant and equipment and accumulated depreciation [Abstract]
Minimum estimated useful life (in years)					5
Maximum estimated useful life (in years)					35

[1] Depreciation expense is a component of "Costs and expenses" as presented on our Unaudited Condensed Statements of Consolidated Operations.

[2] Capitalized interest increases the carrying value of the associated asset and reduces interest expense during the period it is recorded.

[3] In general, the estimated useful lives of major assets within this category are: processing plants, 20-35 years; pipelines and related equipment, 5-45 years; terminal facilities, 10-35 years; office furniture and equipment, 3-20 years; buildings, 20-40 years; and laboratory and shop equipment, 5-35 years.

[4] Plants and pipelines include processing plants; NGL, natural gas, crude oil and petrochemical and refined products pipelines; terminal loading and unloading facilities; office furniture and equipment; buildings; laboratory and shop equipment and related assets.

[5] In general, the estimated useful lives of assets within this category are: underground storage facilities, 5-35 years; storage tanks, 10-40 years; and water wells, 5-35 years.

[6] Underground and other storage facilities include underground product storage caverns; above ground storage tanks; water wells and related assets.

[7] Platforms and facilities include offshore platforms and related facilities and other associated assets located in the Gulf of Mexico.

[8] Transportation equipment includes tractor-trailer tank trucks and other vehicles and similar assets used in our operations.

[9] Marine vessels include tow boats, barges and related equipment used in our marine transportation business.