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
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 GTN and Bison	Dec. 31, 2012 GTN and Bison	Jun. 30, 2013 Bison	Mar. 31, 2013 Great Lakes	Sep. 30, 2013 General Partner	Sep. 30, 2012 General Partner	Sep. 30, 2013 General Partner	Sep. 30, 2012 General Partner	Sep. 30, 2013 TransCanada Corporation GTN	Sep. 30, 2012 TransCanada Corporation GTN	Sep. 30, 2013 TransCanada Corporation GTN	Sep. 30, 2012 TransCanada Corporation GTN	Dec. 31, 2012 TransCanada Corporation GTN	Sep. 30, 2013 TransCanada Corporation Bison	Sep. 30, 2012 TransCanada Corporation Bison	Sep. 30, 2013 TransCanada Corporation Bison	Sep. 30, 2012 TransCanada Corporation Bison	Dec. 31, 2012 TransCanada Corporation Bison	Sep. 30, 2013 TransCanada Corporation North Baja	Sep. 30, 2012 TransCanada Corporation North Baja	Sep. 30, 2013 TransCanada Corporation North Baja	Sep. 30, 2012 TransCanada Corporation North Baja	Dec. 31, 2012 TransCanada Corporation North Baja	Sep. 30, 2013 TransCanada Corporation Tuscarora	Sep. 30, 2012 TransCanada Corporation Tuscarora	Sep. 30, 2013 TransCanada Corporation Tuscarora	Sep. 30, 2012 TransCanada Corporation Tuscarora	Dec. 31, 2012 TransCanada Corporation Tuscarora	Sep. 30, 2013 TransCanada Corporation Great Lakes	Sep. 30, 2012 TransCanada Corporation Great Lakes	Sep. 30, 2013 TransCanada Corporation Great Lakes	Sep. 30, 2012 TransCanada Corporation Great Lakes	Dec. 31, 2012 TransCanada Corporation Great Lakes	Sep. 30, 2013 TransCanada Corporation Northern Border	Sep. 30, 2012 TransCanada Corporation Northern Border	Sep. 30, 2013 TransCanada Corporation Northern Border	Sep. 30, 2012 TransCanada Corporation Northern Border	Dec. 31, 2012 TransCanada Corporation Northern Border	Jun. 30, 2013 Former parent, TransCanada Subsidiaries Bison
Costs charged to the pipeline system and amounts payable
Costs charged by TransCanada and its affiliates							$ 1	$ 1	$ 3	$ 2	$ 7	$ 7	$ 21	$ 21		$ 1	$ 1	$ 4	$ 4		$ 1	$ 1	$ 3	$ 3		$ 1	$ 1	$ 3	$ 3		$ 7	$ 8	$ 23	$ 24		$ 7	$ 7	$ 21	$ 22
Impact on the Partnership's net income											5	2	14	5		1		3	1		1	1	3	3		1	1	3	3		3	4	10	11		3	3	10	10
Amounts payable to TransCanada and its affiliates											3		3		3					1					1					1	2		2		4	3		3		4
Percentage of capital and operating costs charged by TransCanada's subsidiaries													100.00%					100.00%															100.00%					100.00%
Transportation revenues from TransCanada and its affiliates																															14	17	49	58
Percentage of transportation revenues to total revenues																															54.00%	37.00%	54.00%	41.00%
Affiliated rental revenue																															1	1	1	1
Revenue from TransCanada and its affiliates included in the Partnership's equity earnings from Great Lakes																															7	8	23	27
Great Lakes' receivables for transportation contracts with TransCanada and its affiliates																															5		5		10
Capital contribution																																									18
Ownership interest																																									75.00%
Total cash call issued to fund debt repayment					24	9
Demand loan receivable from affiliate	45	21	45	21
Demand loan payable to affiliate		$ 15		$ 15