INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Apr. 30, 2006	Mar. 31, 2014	Mar. 31, 2013		Dec. 31, 2013
Investments in unconsolidated affiliates
Equity Earnings from Unconsolidated Affiliates		$ 33	$ 18	[1]
Investments in Unconsolidated Affiliates		1,206			1,195
Northern Border
Investments in unconsolidated affiliates
Ownership interest at the end of the period (as a percent)		50.00%
Equity Earnings from Unconsolidated Affiliates		23	16
Investments in Unconsolidated Affiliates		525			523
Amortization period of transaction fee	12 years
Transaction fee	10
Additional ownership interest acquired (as a percent)	20.00%
Undistributed earnings		0	0
Assets
Cash and cash equivalents		40			27
Other current assets		44			34
Plant, property and equipment, net		1,191			1,197
Other assets		32			33
Assets, total		1,307			1,291
LIABILITIES AND PARTNERS' EQUITY
Current liabilities		62			51
Deferred credits and other		20			19
Long-term debt, including current maturities		411			411
Partners' equity
Partners' equity		816			812
Accumulated other comprehensive loss		(2)			(2)
Liabilities and Equity, total		1,307			1,291
Revenues (expenses)
Transmission revenues		86	72
Operating expenses		(18)	(19)
Depreciation		(15)	(15)
Financial charges and other		(6)	(5)
Net income		47	33
Great Lakes
Investments in unconsolidated affiliates
Ownership interest at the end of the period (as a percent)		46.45%
Equity Earnings from Unconsolidated Affiliates		10	2
Investments in Unconsolidated Affiliates		681			672
Undistributed earnings		0	0
Equity contribution		4	4	[1]
Total cash call issued to fund debt repayment		9
Assets
Current assets		69			52
Plant, property and equipment, net		764			771
Assets, total		833			823
LIABILITIES AND PARTNERS' EQUITY
Current liabilities		28			28
Long-term debt, including current maturities		326			335
Partners' equity
Partners' equity		479			460
Liabilities and Equity, total		833			823
Revenues (expenses)
Transmission revenues		48	35
Operating expenses		(12)	(15)
Depreciation		(7)	(8)
Financial charges and other		(7)	(7)
Net income		$ 22	$ 5

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