INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended				3 Months Ended	1 Months Ended	3 Months Ended				9 Months Ended					3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013		Dec. 31, 2013	Mar. 31, 2014 Great Lakes	Apr. 30, 2006 Northern Border	Sep. 30, 2014 Northern Border		Sep. 30, 2013 Northern Border		Sep. 30, 2014 Northern Border		Sep. 30, 2013 Northern Border		Dec. 31, 2013 Northern Border	Sep. 30, 2014 Great Lakes	Mar. 31, 2014 Great Lakes	Sep. 30, 2013 Great Lakes	Sep. 30, 2014 Great Lakes	Sep. 30, 2013 Great Lakes		Dec. 31, 2013 Great Lakes
Investments in unconsolidated affiliates
Ownership interest at the end of the period (as a percent)									50.00%				50.00%					46.45%	46.45%		46.45%
Equity Earnings (Loss) from Unconsolidated Affiliates	$ 15	$ 15	$ 66	$ 48	[1]				$ 14	[2]	$ 17	[2]	$ 53	[2]	$ 48	[2]		$ 1		$ (2)	$ 13
Investments in Unconsolidated Affiliates	1,174		1,174			1,195			508				508				523	666			666			672
Amortization period of transaction fee								12 years
Transaction fee								10
Additional ownership interest acquired (as a percent)								20.00%
Equity contribution																			4		4	4	[1]
Undistributed earnings													0		0						0	0
Total cash call issued to fund debt repayment							9
Assets
Cash and cash equivalents									42				42				27
Current assets																		46			46			52
Other current assets									32				32				34
Plant, property and equipment, net									1,173				1,173				1,197	752			752			771
Other assets									34				34				33
Assets, total									1,281				1,281				1,291	798			798			823
LIABILITIES AND PARTNERS' EQUITY
Current liabilities									67				67				51	26			26			28
Deferred credits and other									22				22				19
Long-term debt, including current maturities									411				411				411	326			326			335
Partners' equity
Partners' equity									783				783				812	446			446			460
Accumulated other comprehensive loss									(2)				(2)				(2)
Liabilities and Equity, total									1,281				1,281				1,291	798			798			823
Revenues (expenses)
Transmission revenues									66		72		221		213			29		26	106	90
Operating expenses									(16)		(18)		(50)		(56)			(14)		(15)	(38)	(45)
Depreciation									(15)		(15)		(44)		(44)			(7)		(8)	(21)	(24)
Financial charges and other									(8)		(6)		(20)		(17)			(6)		(6)	(19)	(20)
Net income (loss)									$ 27		$ 33		$ 107		$ 96			$ 2		$ (3)	$ 28	$ 1

[1] Recast as discussed in Note 2.

[2] Equity earnings from Northern Border is net of the 12-year amortization of a $10 million transaction fee paid to the operator of Northern Border at the time of the Partnership’s additional 20 percent interest acquisition in April 2006.