ORGANIZATION (Details)	12 Months Ended
	Dec. 31, 2011 miles	Feb. 02, 2012
Great Lakes
Organization
Ownership interest (as a percent)	46.45%	46.45%
Length of the pipeline owned by equity method investee (in miles)	2,115
Northern Border
Organization
Ownership interest (as a percent)	50.00%	50.00%
Length of the pipeline owned by equity method investee (in miles)	1,407
GTN
Organization
Ownership interest (as a percent)	25.00%	25.00%
Length of the pipeline owned by equity method investee (in miles)	1,353
Bison
Organization
Ownership interest (as a percent)	25.00%	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%
Length of the pipeline owned by equity method investee (in miles)	86
Tuscarora Gas Transmission Company
Organization
Partnership interest held (as a percent)	100.00%
Length of the pipeline owned by equity method investee (in miles)	305