SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Debt (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Maturities of Debt
2016		$ 395,344
2017		90,000
2018		685,000
2019		319,900
2020		235,000
2021 and thereafter		2,735,340
Total		4,460,584
Fair Value Disclosures [Abstract]
Fair value of long-term debt and debt maturing within one year, excluding revolving and term loan credit agreements and commercial paper		3,879,700	$ 3,985,600
Book value of long-term debt and debt maturing within one year, excluding revolving and term loan credit agreements and commercial paper		3,680,400	3,629,800
Book value of revolving credit agreements and term loan credit agreements		680,900	473,800
Commercial paper	[1]	94,990
ITC Holdings Corp.
Maturities of Debt
2016		395,344
2017		50,000
2018		385,000
2019		137,700
2020		200,000
2021 and thereafter		1,150,340
Total		2,318,384
Fair Value Disclosures [Abstract]
Fair value of long-term debt and debt maturing within one year, excluding revolving and term loan credit agreements and commercial paper		2,059,400	2,126,100
Book value of long-term debt and debt maturing within one year, excluding revolving and term loan credit agreements and commercial paper		1,921,300	1,920,700
Book value of revolving credit agreements and term loan credit agreements		$ 298,700	$ 214,500

[1] As of December 31, 2015 and 2014, there was $395.3 million and $175.0 million, respectively, of debt included within debt maturing within one year that is classified as a current liability in the consolidated statements of financial position.