ORGANIZATION (Details)	6 Months Ended
Jun. 30, 2011
Great Lakes
Organization
Ownership interest (as a percent)	46.45%
Northern Border
Organization
Ownership interest (as a percent)	50.00%
GTN
Organization
Ownership interest (as a percent)	25.00%
Length of the pipeline owned by equity method investee (in miles)	1,353
Bison
Organization
Ownership interest (as a percent)	25.00%
Length of the pipeline owned by equity method investee (in miles)	303
North Baja Pipeline, LLC
Organization
Partnership interest held (as a percent)	100.00%
Tuscarora Gas Transmission Company
Organization
Partnership interest held (as a percent)	100.00%

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 3: 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

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Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant