SUBSEQUENT EVENTS (Details) (USD $) In Millions, except Share data, unless otherwise specified							12 Months Ended							12 Months Ended			0 Months Ended		12 Months Ended	0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Great Lakes	Feb. 28, 2007 Great Lakes	Dec. 31, 2013 Northern Border	Dec. 31, 2013 GTN	Dec. 31, 2013 Bison	Dec. 31, 2013 Common units	Dec. 31, 2012 Common units	Dec. 31, 2011 Common units	Dec. 31, 2013 Common units TC PipeLines GP, Inc.	Dec. 31, 2013 Common units TransCanada	Dec. 31, 2013 General Partner	Dec. 31, 2012 General Partner	Dec. 31, 2011 General Partner	May 22, 2013 General Partner TC PipeLines GP, Inc.	May 03, 2011 General Partner TC PipeLines GP, Inc.	Dec. 31, 2013 General Partner TC PipeLines GP, Inc.	Jan. 16, 2014 Subsequent event	Feb. 03, 2014 Subsequent event GTN	Jan. 09, 2014 Subsequent event GTN	Feb. 03, 2014 Subsequent event Bison	Jan. 09, 2014 Subsequent event Bison	Feb. 14, 2014 Subsequent event General Partner TC PipeLines GP, Inc.	Feb. 03, 2014 Subsequent event Distribution declared Northern Border	Jan. 09, 2014 Subsequent event Distribution declared Great Lakes	Feb. 14, 2014 Subsequent event Cash Distribution Paid	Feb. 03, 2014 Subsequent event Cash Distribution Paid Northern Border	Feb. 03, 2014 Subsequent event Cash Distribution Paid Great Lakes	Feb. 14, 2014 Subsequent event Cash Distribution Paid Common units	Feb. 14, 2014 Subsequent event Cash Distribution Paid Common units TC PipeLines GP, Inc.	Feb. 14, 2014 Subsequent event Cash Distribution Paid Common units TransCanada
Subsequent events
Cash distribution (in dollars per unit)																				$ 0.81
Partnership distribution									$ 184	$ 166	$ 152			$ 4	$ 3	$ 3									$ 1	$ 43	$ 12	$ 52			$ 51	$ 5	$ 9
Number of common units owned	62,300,000	53,500,000	53,500,000						62,327,766	53,472,766	53,472,766	5,797,106	11,287,725
General partner ownership interest in the partnership (as a percent)																	2.00%	2.00%	2.00%
Aggregate distribution declared and payable by investee																						28		17
Partnership interest (as a percent)							70.00%	70.00%
Distribution received by Partnership																					20		12
Ownership interest (as a percent)				46.45%	46.45%	50.00%
Partnership's share of distributions declared and payable by investee																													$ 21	$ 5