PARTNERS' EQUITY - Class B Units (Details) - USD ($)	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Class B units
Partners' Equity
Net income allocated to limited partners	$ 11,000,000	$ 1,000,000		$ 2,000,000		$ 12,000,000	$ 2,000,000
Distribution declared			$ 12,000,000
Distribution paid			$ 12,000,000			12,000,000
GTN
Partners' Equity
30% of GTN's distributable cash flow						$ 32,000,000
GTN | TransCanada | Distributions | Class B units
Partners' Equity
Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)						30.00%
Percentage applied to 30 percent of GTN's distributions above threshold through March 31, 2020						100.00%
Threshold of GTN's total distributable cash flows for payment to Class B units						$ 20,000,000
Percentage applied to GTN's distributions above threshold after March 31, 2020						25.00%
Percentage applied to GTN's distributable cash flow for the twelve month period ending December 31, 2016						30.00%
30% of GTN's distributable cash flow					$ 17,000,000	$ 32,000,000