ORGANIZATION (Details)	12 Months Ended		12 Months Ended		12 Months Ended
Dec. 31, 2012 North Baja Pipeline, LLC mi	Dec. 31, 2012 Tuscarora Gas Transmission Company mi	Dec. 31, 2012 Great Lakes mi	Feb. 28, 2007 Great Lakes	Dec. 31, 2012 Northern Border mi	Dec. 31, 2012 GTN mi	May 03, 2011 GTN	Dec. 31, 2012 Bison mi	May 03, 2011 Bison
Organization
Ownership interest (as a percent)			46.45%	46.45%	50.00%	25.00%	25.00%	25.00%	25.00%
Partnership interest held (as a percent)	100.00%	100.00%
Length of the pipeline owned by equity method investee (in miles)	86	305	2,115		1,408	1,353		303

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant