SUBSEQUENT EVENTS (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended			3 Months Ended		0 Months Ended
	Mar. 31, 2013 Great Lakes	Sep. 30, 2013 Great Lakes	Sep. 30, 2012 Great Lakes	Sep. 30, 2013 Northern Border	Dec. 31, 2013 Subsequent event Great Lakes Expected	Dec. 31, 2013 Subsequent event Northern Border Expected	Oct. 24, 2013 Subsequent event Distribution declared	Oct. 22, 2013 Subsequent event Distribution declared Great Lakes	Oct. 22, 2013 Subsequent event Distribution declared Northern Border	Oct. 22, 2013 Subsequent event Distribution declared GTN	Oct. 22, 2013 Subsequent event Distribution declared Bison	Nov. 01, 2013 Subsequent event Cash Distribution Paid Great Lakes Expected	Nov. 01, 2013 Subsequent event Cash Distribution Paid Northern Border Expected
Subsequent events
Cash distribution (in dollars per unit)							$ 0.81
Aggregate distribution declared and payable by investee								$ 3	$ 38	$ 30	$ 11
Ownership interest (as a percent)		46.45%		50.00%								46.45%	50.00%
Partnership's share of distributions declared and payable by investee												2	19
Equity contribution	$ 4	$ 4	$ 4		$ 5	$ 31