CONSOLIDATED STATEMENT OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
CONSOLIDATED STATEMENT OF INCOME
Equity earnings from unconsolidated affiliates (Note 4)	$ 129	[1]	$ 154	[1]	$ 126
Transmission revenues	65		70		69
Operating expenses	(17)		(15)		(13)
General and administrative	(6)		(9)		(4)
Depreciation	(11)		(15)		(15)
Financial charges and other (Note 9)	(23)		(28)		(26)
Net income	137	[1]	157	[1]	137	[1]
Net income allocation (Note 10)
Common units	134		154		134
General Partner	3		3		3
Net income allocated to partners	$ 137		$ 157		$ 137
Net income per common unit (Note 10) - basic (in dollars per unit)	$ 2.51		$ 3.02		$ 2.91
Net income per common unit (Note 10) - diluted (in dollars per unit)	$ 2.51		$ 3.02		$ 2.91
Weighted average common units outstanding (millions) - basic (in units)	53.5		51.1		46.2
Weighted average common units outstanding (millions) - diluted (in units)	53.5		51.1		46.2
Common units outstanding, end of year (millions) (in units)	53.5		53.5		46.2

[1] 25 percent interests in each of GTN and Bison were acquired in May 2011.