CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
CONSOLIDATED STATEMENTS OF INCOME
Transmission revenues	$ 336	$ 341	[1]	$ 343	[1]
Equity earnings from unconsolidated affiliates (Note 4)	88	67	[1]	99	[1]
Operation and maintenance expenses	(54)	(55)	[1]	(57)	[1]
Property taxes	(21)	(23)	[1]	(25)	[1]
General and administrative	(9)	(9)	[1]	(6)	[1]
Depreciation	(86)	(86)	[1]	(85)	[1]
Financial charges and other (Note 11)	(50)	(44)	[1]	(40)	[1]
Net income	204	191	[1]	229	[1]
Net income attributable to non-controlling interests	32	36	[1]	37	[1]
Net income attributable to controlling interests	172	155	[1]	192	[1]
Net income attributable to controlling interests allocation (Note 12)
Common units	168	126	[1]	134	[1]
General Partner	4	3	[1]	3	[1]
Net income allocated to controlling interests	$ 172	$ 129	[1]	$ 137	[1]
Net income per common unit (Note 12) - basic (in dollars per unit)	$ 2.67	$ 2.13		$ 2.51
Net income per common unit (Note 12) - diluted (in dollars per unit)	$ 2.67	$ 2.13		$ 2.51
Weighted average common units outstanding (millions) - basic (in units)	62.7	58.9		53.5
Weighted average common units outstanding (millions) - diluted (in units)	62.7	58.9		53.5
Common units outstanding, end of year (millions) (in units)	63.6	62.3		53.5

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