INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended						0 Months Ended	12 Months Ended			12 Months Ended		1 Months Ended	3 Months Ended	12 Months Ended					0 Months Ended	3 Months Ended		12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011		Jan. 02, 2013 Northern Border Pipeline Company (general partnership)	Dec. 31, 2013 Northern Border Pipeline Company (general partnership)	Dec. 31, 2013 Northern Border Pipeline Company (general partnership) ONEOK Partners, L.P.	Dec. 31, 2013 Great Lakes Gas Transmission Limited Partnership TransCanada	Dec. 31, 2013 TC GL Intermediate Limited Partnership	Dec. 31, 2013 TC PipeLines Intermediate Limited Partnership	Apr. 30, 2006 Northern Border	Dec. 31, 2013 Northern Border	Dec. 31, 2013 Northern Border		Dec. 31, 2012 Northern Border	Dec. 31, 2011 Northern Border		Nov. 14, 2013 Great Lakes	Dec. 31, 2013 Great Lakes	Mar. 31, 2013 Great Lakes	Dec. 31, 2013 Great Lakes		Dec. 31, 2012 Great Lakes		Dec. 31, 2011 Great Lakes		Feb. 28, 2007 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 from Unconsolidated Affiliates	$ 19	$ 15	$ 15	$ 18	$ 22		$ 24	$ 24	$ 29	$ 67	[1]	$ 99	[1]	$ 135	[1]									$ 64		$ 72	$ 75					$ 3		$ 27		$ 60
Investments in Unconsolidated Affiliates	1,195				1,189	[1]				1,195		1,189	[1]										523	523		512				672		672		677
Amortization period of transaction fee																						12 years
Transaction fee																						10
Additional ownership interest acquired (as a percent)																						20.00%
Other ownership interest (as a percent)																		50.00%	53.55%
Partnership interest held (as a percent)																				98.9899%	98.9899%
Term of moratorium on filing rate cases																3 years
Reduction in current transportation rates (as a percent)																	11.00%
Increase in transportation rates compared to current rates (as a percent)																													21.00%
Undistributed earnings																								0		0	0					0		0		0
Amount of difference between the carrying value and the underlying equity in net assets resulting from the recognition and inclusion of goodwill																							118	118		119				458		458		458
Equity contribution																							31	31	[1]		55	[1]		5	4	9	[1]	9	[1]	9	[1]
Total cash call issued to fund debt repayment																							62							10	9
Assets
Cash and cash equivalents																							27	27		28
Current assets																														52		52		56
Other current assets																							34	34		35
Plant, property and equipment, net																							1,197	1,197		1,234				771		771		799
Other assets																							33	33		31
Assets, total																							1,291	1,291		1,328				823		823		855
Liabilities and Partners' Equity
Current liabilities																							51	51		53				28		28		30
Deferred credits and other																							19	19		16
Long-term debt, including current maturities																							411	411		473				335		335		354
Partners' equity
Partners' equity																							812	812		789				460		460		471
Accumulated other comprehensive loss																							(2)	(2)		(3)
Liabilities and Equity, total																							1,291	1,291		1,328				823		823		855
Revenues (expenses)
Transmission revenues																								286		311	310					124		182		250
Operating expenses																								(75)		(79)	(73)					(60)		(66)		(62)
Depreciation																								(58)		(63)	(62)					(31)		(31)		(32)
Financial charges and other																								(23)		(24)	(22)					(27)		(28)		(30)
Michigan business tax																																				2
Net income																								$ 130		$ 145	$ 153					$ 6		$ 57		$ 128

[1] (a) Recast as discussed in Note 2 and Note 6.