CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Transmission revenues	$ 101	$ 101	[1]	$ 213		$ 212	[1]
Equity earnings (Note 4)	24	20	[1]	60		53	[1]
Operation and maintenance expenses	(17)	(14)	[1]	(31)		(25)	[1]
Property taxes	(7)	(7)	[1]	(14)		(14)	[1]
General and administrative	(2)	(2)	[1]	(4)		(4)	[1]
Depreciation	(25)	(24)	[1]	(49)		(48)	[1]
Financial charges and other (Note 14)	(19)	(17)	[1]	(36)		(35)	[1]
Net income before taxes	55	57	[1]	139		139	[1]
Income taxes (Note 18)				(1)		(1)	[1]
Net income	55	57	[1]	138	[2]	138	[1]
Net income attributable to non-controlling interests		2	[1]	6		8	[1]
Net income attributable to controlling interests	55	55	[1]	132		130	[1]
Net income attributable to controlling interest allocation (Note 8)
General Partner	5	3	[1]	8		5	[1]
TransCanada and its subsidiaries		2	[1]	2		4	[1]
Net income attributable to controlling interests	55	55	[1]	132		130	[1]
Common Units
Net income attributable to controlling interest allocation (Note 8)
Limited partners	$ 50	$ 50	[1]	$ 122		$ 121	[1]
Net income per common unit (Note 8) - basic (in dollars per unit)	$ 0.73	$ 0.76	[1],[3]	$ 1.78		$ 1.86	[1],[3]
Net income per common unit (Note 8) - diluted (in dollars per unit)	$ 0.73	$ 0.76		$ 1.78		$ 1.86
Weighted average common units outstanding - basic (in units)	68.9	65.5	[1]	68.6		64.9	[1]
Weighted average common units outstanding - diluted (in units)	68.9	65.5		68.6		64.9
Common units outstanding, end of period (in units)	69.0	65.9	[1]	69.0		65.9	[1]

[1] Recast to consolidate PNGTS for all periods presented (Refer to Notes 2 and 6).

[2] Recast to consolidate PNGTS for all periods presented. See Notes 2 and 6.

[3] Net income per common unit prior to recast (Refer to Note 2).