The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Intangible Assets and Goodwill (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Identifiable intangible assets [Abstract]
Gross Value	$ 2,618.5		$ 2,618.5		$ 2,646.6
Accumulated Amortization	(1,022.4)		(1,022.4)		(990.4)
Carrying Value	1,596.1		1,596.1		1,656.2
Amortization Expense	32.3	37.0	95.9	112.1
Forecasted amortization expense [Abstract]
Remainder of 2012	28.0		28.0
2013	114.6		114.6
2014	109.8		109.8
2015	108.4		108.4
2016	106.8		106.8
NGL Pipelines and Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	625.5		625.5		639.2
Accumulated Amortization	(295.1)		(295.1)		(297.9)
Carrying Value	330.4		330.4		341.3
Amortization Expense	10.1	10.3	29.9	30.7
NGL Pipelines and Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	340.8		340.8		340.8
Accumulated Amortization	(143.0)		(143.0)		(128.2)
Carrying Value	197.8		197.8		212.6
NGL Pipelines and Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	284.7		284.7		298.4
Accumulated Amortization	(152.1)		(152.1)		(169.7)
Carrying Value	132.6		132.6		128.7
Onshore Natural Gas Pipelines And Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	1,631.9		1,631.9		1,628.4
Accumulated Amortization	(549.0)		(549.0)		(500.6)
Carrying Value	1,082.9		1,082.9		1,127.8
Amortization Expense	16.8	19.5	48.4	59.6
Onshore Natural Gas Pipelines And Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	1,163.6		1,163.6		1,163.6
Accumulated Amortization	(240.9)		(240.9)		(209.7)
Carrying Value	922.7		922.7		953.9
Onshore Natural Gas Pipelines And Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	468.3		468.3		464.8
Accumulated Amortization	(308.1)		(308.1)		(290.9)
Carrying Value	160.2		160.2		173.9
Onshore Crude Oil Pipelines and Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	10.5		10.5		10.1
Accumulated Amortization	(4.8)		(4.8)		(4.3)
Carrying Value	5.7		5.7		5.8
Amortization Expense	0.2	0.1	0.5	0.3
Onshore Crude Oil Pipelines and Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	10.1		10.1		9.7
Accumulated Amortization	(4.6)		(4.6)		(4.1)
Carrying Value	5.5		5.5		5.6
Onshore Crude Oil Pipelines and Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	0.4		0.4		0.4
Accumulated Amortization	(0.2)		(0.2)		(0.2)
Carrying Value	0.2		0.2		0.2
Offshore Pipelines And Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	205.1		205.1		207.0
Accumulated Amortization	(135.9)		(135.9)		(129.5)
Carrying Value	69.2		69.2		77.5
Amortization Expense	3.1	2.8	8.3	8.6
Offshore Pipelines And Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	203.9		203.9		205.8
Accumulated Amortization	(135.5)		(135.5)		(129.2)
Carrying Value	68.4		68.4		76.6
Offshore Pipelines And Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	1.2		1.2		1.2
Accumulated Amortization	(0.4)		(0.4)		(0.3)
Carrying Value	0.8		0.8		0.9
Petrochemical and Refined Products Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	145.5		145.5		161.9
Accumulated Amortization	(37.6)		(37.6)		(58.1)
Carrying Value	107.9		107.9		103.8
Amortization Expense	2.1	4.3	8.8	12.9
Petrochemical and Refined Products Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	104.3		104.3		104.3
Accumulated Amortization	(32.1)		(32.1)		(28.4)
Carrying Value	72.2		72.2		75.9
Petrochemical and Refined Products Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	41.2		41.2		57.6
Accumulated Amortization	(5.5)		(5.5)		(29.7)
Carrying Value	$ 35.7		$ 35.7		$ 27.9