CONSOLIDATED STATEMENTS OF OPERATIONS shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares		Dec. 31, 2017 USD ($) $ / shares shares		Dec. 31, 2016 USD ($) $ / shares shares	[1]
Transmission revenues	$ 549		$ 422		$ 426
Equity earnings (Note 5)	173		124		97
Impairment of long lived assets (Note 7)	(537)
Impairment of goodwill (Note 4)	(59)
Operation and maintenance expenses	(67)		(67)		(58)
Property taxes	(28)		(28)		(27)
General and administrative	(6)		(8)		(7)
Depreciation	(97)		(97)		(96)
Financial charges and other (Note 13)	(92)		(82)		(71)
Net income (loss) before taxes	(164)		264		264
Income taxes (Note 24)	(1)		(1)		(1)
Net Income (loss)	(165)	[1]	263	[1]	263
Net income attributable to non-controlling interests	17		11		15
Net income (loss) attributable to controlling interests	(182)		252		248
Net income (loss) attributable to controlling interest allocation (Note 14)
General Partner	(4)		16		11
TransCanada and its subsidiaries	13		17		26
Net income attributable to controlling interests	(182)		252		248
Common Units
Net income (loss) attributable to controlling interest allocation (Note 14)
Net income (loss) attributable to common units	$ (191)		$ 219		$ 211
Net income (loss) per common unit (Note 14) - basic and diluted | $ / shares	$ (2.68)	[2]	$ 3.16	[2]	$ 3.21	[2]
Weighted average common units outstanding - basic and diluted (in units) | shares	71.3		69.2		65.7
Common units outstanding, end of year | shares	71.3		70.6		67.4

[1] Recast to consolidate PNGTS (Refer to Notes 2 and 8).

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