SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Statements of Comprehensive Income (Parent Company) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2015	[1],[2]	Sep. 30, 2015	[1],[2]	Jun. 30, 2015	[1],[2]	Mar. 31, 2015	[1],[2]	Dec. 31, 2014	[2],[3]	Sep. 30, 2014	[2],[3]	Jun. 30, 2014	[2],[3]	Mar. 31, 2014	[2],[3]	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Condensed Financial Statements, Captions
NET INCOME	$ 37,365		$ 65,573		$ 72,336		$ 67,132		$ 46,738		$ 73,873		$ 54,336		$ 69,136		$ 242,406	[1],[2]	$ 244,083	[2],[3]	$ 233,506
OTHER COMPREHENSIVE (LOSS) INCOME
Derivative instruments (net of tax of $967, $1,897 and $16,087 for the years ended December 31, 2015, 2014 and 2013, respectively)																	(375)		(1,479)		24,304
Available-for-sale securities (net of tax of $126, $18 and $46 for the years ended December 31, 2015, 2014 and 2013, respectively)																	(176)		(32)		71
TOTAL OTHER COMPREHENSIVE (LOSS) INCOME, NET OF TAX																	(551)		(1,511)		24,375
TOTAL COMPREHENSIVE INCOME																	241,855		242,572		257,881
ITC Holdings Corp.
Condensed Financial Statements, Captions
NET INCOME																	242,406		244,083		233,506
OTHER COMPREHENSIVE (LOSS) INCOME
Derivative instruments (net of tax of $967, $1,897 and $16,087 for the years ended December 31, 2015, 2014 and 2013, respectively)																	(375)		(1,479)		24,304
Available-for-sale securities (net of tax of $126, $18 and $46 for the years ended December 31, 2015, 2014 and 2013, respectively)																	(176)		(32)		71
TOTAL OTHER COMPREHENSIVE (LOSS) INCOME, NET OF TAX																	(551)		(1,511)		24,375
TOTAL COMPREHENSIVE INCOME																	241,855		242,572		257,881
Statements of Comprehensive Income, Additional Disclosures
Derivative instruments, tax																	967		1,897		16,087
Available-for-sale securities, tax																	$ 126		$ 18		$ 46

[1] During the third and fourth quarters of 2015, we recognized an aggregate regulatory liability for the refund relating to the formula rate template modifications filing as described in Note 4, which resulted in a reduction in operating revenues and operating income of $9.5 million and an estimated $6.2 million reduction to net income for the year ended December 31, 2015.

[2] During the year ended December 31, 2015 and the fourth quarter of 2014, we recognized an aggregate estimated regulatory liability for the potential refunds relating to the ROE complaints as described in Note 16, which resulted in a reduction in operating revenues and operating income of $115.1 million and $46.9 million and an estimated $73.2 million and $28.9 million reduction to net income for the years ended December 31, 2015 and 2014, respectively.

[3] During the second quarter of 2014, we incurred a loss on extinguishment of debt of $29.2 million related to the tender of ITC Holdings Senior Notes as described in Note 8, which resulted in an estimated reduction to net income of $18.2 million.