Intangible Assets and Goodwill, Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Identifiable intangible assets [Abstract]
Gross Value	$ 5,267.2	$ 5,273.0
Accumulated Amortization	(1,403.1)	(1,235.8)
Carrying Value	3,864.1	4,037.2	$ 4,302.1
Amortization expense	171.3	174.1	110.6
Forecasted amortization expense [Abstract]
2017	161.7
2018	163.8
2019	157.7
2020	152.8
2021	163.2
Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Carrying Value	3,500.0
Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Carrying Value	367.6
NGL Pipelines & Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	727.3	730.4
Accumulated Amortization	(377.1)	(350.1)
Carrying Value	350.2	380.3
Amortization expense	30.6	33.6	33.1
NGL Pipelines & Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	447.4	447.4
Accumulated Amortization	(172.7)	(156.9)
Carrying Value	274.7	290.5
NGL Pipelines & Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	279.9	283.0
Accumulated Amortization	(204.4)	(193.2)
Carrying Value	75.5	89.8
Crude Oil Pipelines & Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	2,485.4	2,485.8
Accumulated Amortization	(206.4)	(108.3)
Carrying Value	2,279.0	2,377.5
Amortization expense	98.4	87.1	15.7
Crude Oil Pipelines & Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	2,204.4	2,204.4
Accumulated Amortization	(84.5)	(39.1)
Carrying Value	2,119.9	2,165.3
Crude Oil Pipelines & Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	281.0	281.4
Accumulated Amortization	(121.9)	(69.2)
Carrying Value	159.1	212.2
Natural Gas Pipelines & Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	1,815.0	1,815.0
Accumulated Amortization	(760.5)	(727.3)
Carrying Value	1,054.5	1,087.7
Amortization expense	33.2	40.0	45.0
Natural Gas Pipelines & Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	1,350.3	1,350.3
Accumulated Amortization	(390.0)	(366.3)
Carrying Value	960.3	984.0
Natural Gas Pipelines & Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	464.7	464.7
Accumulated Amortization	(370.5)	(361.0)
Carrying Value	94.2	103.7
Petrochemical & Refined Products Services [Member]
Identifiable intangible assets [Abstract]
Gross Value	239.5	241.8
Accumulated Amortization	(59.1)	(50.1)
Carrying Value	180.4	191.7
Amortization expense	9.1	8.9	6.9
Petrochemical & Refined Products Services [Member] \| Customer relationship intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	185.5	185.5
Accumulated Amortization	(43.9)	(38.3)
Carrying Value	141.6	147.2
Petrochemical & Refined Products Services [Member] \| Contract-based intangibles [Member]
Identifiable intangible assets [Abstract]
Gross Value	54.0	56.3
Accumulated Amortization	(15.2)	(11.8)
Carrying Value	38.8	44.5
Offshore Pipelines & Services [Member]
Identifiable intangible assets [Abstract]
Amortization expense	$ 0.0	$ 4.5	$ 9.9

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References