CONSOLIDATED STATEMENT OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CONSOLIDATED STATEMENT OF INCOME
Equity earnings from unconsolidated affiliates (Note 4)	$ 26	$ 38
Transmission revenues	17	16
Operating expenses	(4)	(4)
General and administrative	(2)	(2)
Depreciation	(3)	(3)
Financial charges and other	(5)	(6)
Net income	29	39
Net income allocation (Note 6)
Common units	28	38
General Partner	1	1
Net income allocated to partners	$ 29	$ 39
Net income per common unit (Note 6) - basic (in dollars per unit)	$ 0.52	$ 0.71
Net income per common unit (Note 6) - diluted (in dollars per unit)	$ 0.52	$ 0.71
Weighted average common units outstanding (millions) - basic (in units)	53.5	53.5
Weighted average common units outstanding (millions) - diluted (in units)	53.5	53.5
Common units outstanding, end of period (millions) (in units)	53.5	53.5