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The number of the Partnership's class B units owned by the holding company.

+ References

No definition available.

+ Details

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- Definition

The number of the Partnership's common units owned by the holding company.

+ References

No definition available.

+ Details

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- Definition

The percentage of the Partnership's equity interests owned by the holding company.

+ References

No definition available.

+ Details

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- Definition

The percent of the general partner interest owned by the holding company.

+ References

No definition available.

+ Details

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

The amount of a reclassification adjustment made to prior period financial statement amounts.

+ References

No definition available.

+ Details

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Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2013 Minimum [Member]	Jun. 30, 2013 Maximum [Member]	Jul. 30, 2013 Boardwalk Pipelines Holding Company [Member]	Jul. 30, 2013 Boardwalk GP, LP [Member]
Basis of Presentation [Line Items]
Equity Method Investment, Ownership Percentage				20.00%	50.00%
Number Of Partnerships Common Units Owned By Holding Company						102.7
Number of Partnership's class B units owned by holding company (in units)						22.9
Percent of general partner interest owned by holding company	2.00%	2.00%	2.00%				2.00%
Percentage of Partnership's equity interests owned by holding company (in hundredths)						53.00%
Prior Period Reclassification Adjustment	$ 0.6	$ 0.2