SUBSEQUENT EVENTS (Details 2) (GTN, Former parent, TransCanada subsidiaries, Transaction between entities under common control, USD $) In Millions, unless otherwise specified	0 Months Ended
	Jul. 01, 2013	Feb. 24, 2015
Subsequent events
Interest acquired (as a percent)	45.00%
Purchase price	$ 750
Assumption of proportional debt	146
Subsequent event | Expected
Subsequent events
Interest acquired (as a percent)		30.00%
Purchase price		446
Total cash consideration		253
Assumption of proportional debt		98
Subsequent event | Partnership interest | Class B units | Expected
Subsequent events
Equity issuance		95
Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above $20 million (as a percent)		30.00%
Period for payment of 30 percent of GTN's distributions above $20 million at 100 percent		5 years
Percentage applied to 30 percent of GTN's distributions above $20 million for the first five years		100.00%
Threshold of 30 percent of GTN's annual distributions for payment to Class B units at specified percentage		$ 20
Percentage applied to 30 percent of GTN's distributions above $20 million after the first five years		25.00%