RELATED PARTY TRANSACTIONS (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			0 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 General Partner Reimbursement of costs of services provided	Sep. 30, 2013 General Partner Reimbursement of costs of services provided	Sep. 30, 2014 General Partner Reimbursement of costs of services provided	Sep. 30, 2013 General Partner Reimbursement of costs of services provided	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes	Dec. 31, 2013 TransCanada's subsidiaries Great Lakes	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Transportation contracts	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Transportation contracts	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Transportation contracts	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Transportation contracts	Dec. 31, 2013 TransCanada's subsidiaries Great Lakes Transportation contracts	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Affiliated rental revenue	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Affiliated rental revenue	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Affiliated rental revenue	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Affiliated rental revenue	Sep. 30, 2014 TransCanada's subsidiaries Northern Border	Dec. 31, 2013 TransCanada's subsidiaries Northern Border	Sep. 30, 2014 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries GTN	Dec. 31, 2013 TransCanada's subsidiaries GTN	Sep. 30, 2014 TransCanada's subsidiaries GTN Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries GTN Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries GTN Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries GTN Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Bison	Sep. 30, 2014 TransCanada's subsidiaries Bison Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Bison Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Bison Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Bison Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries North Baja Pipeline, LLC	Dec. 31, 2013 TransCanada's subsidiaries North Baja Pipeline, LLC	Sep. 30, 2014 TransCanada's subsidiaries North Baja Pipeline, LLC Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries North Baja Pipeline, LLC Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries North Baja Pipeline, LLC Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries North Baja Pipeline, LLC Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Tuscarora Gas Transmission Company	Sep. 30, 2014 TransCanada's subsidiaries Tuscarora Gas Transmission Company Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Tuscarora Gas Transmission Company Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Tuscarora Gas Transmission Company Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Tuscarora Gas Transmission Company Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Great Lakes Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2014 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2013 TransCanada's subsidiaries Northern Border Capital and operating costs	Sep. 30, 2014 GTN	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
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 1	$ 1	$ 2	$ 3			$ 7	$ 7	$ 22	$ 23												$ 9	$ 7	$ 26	$ 21			$ 8	$ 7	$ 21	$ 21		$ 2	$ 1	$ 4	$ 4			$ 1	$ 1	$ 3	$ 3		$ 1	$ 1	$ 3	$ 3
Impact on the Partnership's net income attributable to controlling interests																														5	5	14	14		1	1	3	3			1	1	3	3		1	1	3	3					3	3	10	10	4	3	11	10
Accounts payable to affiliates	17	29					13	3														12	3					11	3					1					1	1					1
Percentage of capital and operating costs charged									100.00%	100.00%	100.00%	100.00%												100.00%	100.00%	100.00%	100.00%			100.00%	100.00%	100.00%	100.00%		100.00%	100.00%	100.00%	100.00%
Revenues from related party													13	14	48	49		0	1	1	1
Percentage of revenues from TransCanada and its affiliates to total revenues													46.00%	54.00%	46.00%	54.00%
Revenue from TransCanada and its affiliates included in the Partnership's equity earnings																																																		6	7	23	23
Amount included in receivables from related party													7		7		11
Accrued additional consideration																																																																25
Payment with respect to the Carty Lateral consideration																																																														$ 25	$ 25