RELATED PARTY TRANSACTIONS (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	3 Months Ended		6 Months Ended		0 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 General Partner	Jun. 30, 2013 General Partner	Jun. 30, 2014 General Partner	Jun. 30, 2013 General Partner	Apr. 11, 2014 GTN Former parent, TransCanada subsidiaries Transaction between entities under common control	Dec. 31, 2013 GTN Former parent, TransCanada subsidiaries Transaction between entities under common control Accounts payable to affiliates	Jun. 30, 2014 Northern Border TransCanada's subsidiaries	Jun. 30, 2013 Northern Border TransCanada's subsidiaries	Jun. 30, 2014 Northern Border TransCanada's subsidiaries	Jun. 30, 2013 Northern Border TransCanada's subsidiaries	Jun. 30, 2014 Great Lakes TransCanada's subsidiaries	Jun. 30, 2013 Great Lakes TransCanada's subsidiaries	Jun. 30, 2014 Great Lakes TransCanada's subsidiaries	Jun. 30, 2013 Great Lakes TransCanada's subsidiaries	Jun. 30, 2014 Great Lakes Affiliated rental revenue	Jun. 30, 2013 Great Lakes Affiliated rental revenue	Jun. 30, 2014 Great Lakes Affiliated rental revenue	Jun. 30, 2013 Great Lakes Affiliated rental revenue	Jun. 30, 2014 Great Lakes TransCanada's subsidiaries	Jun. 30, 2013 Great Lakes TransCanada's subsidiaries	Jun. 30, 2014 Great Lakes TransCanada's subsidiaries	Jun. 30, 2013 Great Lakes TransCanada's subsidiaries	Dec. 31, 2013 Great Lakes TransCanada's subsidiaries	Jun. 30, 2014 Great Lakes TransCanada's subsidiaries Transportation contracts	Jun. 30, 2013 Great Lakes TransCanada's subsidiaries Transportation contracts	Jun. 30, 2014 Great Lakes TransCanada's subsidiaries Transportation contracts	Jun. 30, 2013 Great Lakes TransCanada's subsidiaries Transportation contracts	Dec. 31, 2013 Great Lakes TransCanada's subsidiaries Transportation contracts	Jun. 30, 2014 Northern Border TransCanada's subsidiaries	Jun. 30, 2013 Northern Border TransCanada's subsidiaries	Jun. 30, 2014 Northern Border TransCanada's subsidiaries	Jun. 30, 2013 Northern Border TransCanada's subsidiaries	Dec. 31, 2013 Northern Border TransCanada's subsidiaries	Jun. 30, 2014 GTN TransCanada's subsidiaries	Jun. 30, 2013 GTN TransCanada's subsidiaries	Jun. 30, 2014 GTN TransCanada's subsidiaries	Jun. 30, 2013 GTN TransCanada's subsidiaries	Dec. 31, 2013 GTN TransCanada's subsidiaries	Jun. 30, 2014 Bison TransCanada's subsidiaries	Jun. 30, 2013 Bison TransCanada's subsidiaries	Jun. 30, 2014 Bison TransCanada's subsidiaries	Jun. 30, 2013 Bison TransCanada's subsidiaries	Jun. 30, 2014 North Baja TransCanada's subsidiaries	Jun. 30, 2013 North Baja TransCanada's subsidiaries	Jun. 30, 2014 North Baja TransCanada's subsidiaries	Jun. 30, 2013 North Baja TransCanada's subsidiaries	Dec. 31, 2013 North Baja TransCanada's subsidiaries	Jun. 30, 2014 Tuscarora TransCanada's subsidiaries	Jun. 30, 2013 Tuscarora TransCanada's subsidiaries	Jun. 30, 2014 Tuscarora TransCanada's subsidiaries	Jun. 30, 2013 Tuscarora TransCanada's subsidiaries
Capital and operating costs charged to the pipeline systems and amount payable
Capital and operating costs charged by TransCanada's subsidiaries		$ 1	$ 1	$ 2	$ 2															$ 8	$ 8	$ 15	$ 16							$ 10	$ 7	$ 17	$ 14		$ 7	$ 7	$ 13	$ 14		$ 1	$ 2	$ 3	$ 3	$ 1	$ 1	$ 2	$ 2		$ 1	$ 1	$ 2	$ 2
Impact on the Partnership's net income								4	4	7	7	4	3	7	7																				5	5	9	9		1	1	2	2	1	1	2	2		1	1	2	2
Amounts payable to TransCanada's subsidiaries																				14		14		3						15		15		3	13		13		3	2		2		2		2		1	2		2
Percentage of capital and operating costs charged by TransCanada's subsidiaries																						100.00%										100.00%					100.00%					100.00%
Revenues from related party																1		1							13	14	35	35
Percentage of revenues from TransCanada and its affiliates to total revenues																									43.00%	49.00%	46.00%	54.00%
Revenue from TransCanada and its affiliates included in the Partnership's equity earnings												6	6	17	16
Amount included in receivables from related party																									5		5		11
Accrued additional consideration							25
Payment with respect to the Carty Lateral consideration	$ 25					$ 25