REGULATORY ASSETS AND LIABILITIES Regulatory Assets (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2007	Feb. 28, 2003
Regulatory Assets
Current regulatory assets		$ 14,736	$ 5,393
Non-current regulatory assets		233,376	223,712
Regulatory assets		248,112	229,105
Revenue Accruals, Including Accrued Interest
Regulatory Assets
Current regulatory assets	[1]	14,736	5,393
Non-current regulatory assets	[1]	25,670	12,387
Revenue Accruals, Accrued Interest
Regulatory Assets
Current regulatory assets		265	120
Non-current regulatory assets		153	75
Income Taxes Recoverable Related to AFUDC Equity
Regulatory Assets
Non-current regulatory assets		103,465	87,168
Pensions and Postretirement
Regulatory Assets
Non-current regulatory assets		18,981	34,151
Income Taxes Recoverable Related to Implementation of the Michigan Corporate Income Tax
Regulatory Assets
Non-current regulatory assets		8,869	8,869
Accrued Asset Removal Costs
Regulatory Assets
Non-current regulatory assets		12,117	7,337
Other
Regulatory Assets
Non-current regulatory assets		267	2,156
ITCTransmission | ADIT Deferral
Regulatory Assets
Non-current regulatory assets		21,716	24,746
Regulatory assets, accumulated amortization		38,886	35,856
Regulatory assets					$ 60,600
METC | ADIT Deferral
Regulatory Assets
Non-current regulatory assets		21,228	23,587
Regulatory assets, accumulated amortization		21,228	18,869
Regulatory assets				$ 42,500
METC | Regulatory Deferrals
Regulatory Assets
Non-current regulatory assets		8,486	9,257
Regulatory assets, accumulated amortization		6,943	6,172
Regulatory assets				$ 15,400
ITC Great Plains | Start-up, Development and Pre-construction Expenses, Including Associated Carrying Charges
Regulatory Assets
Non-current regulatory assets	[2]	12,577	$ 14,054
Regulatory assets, accumulated amortization		1,000
Regulatory assets		$ 12,600

[1] Refer to discussion of revenue accruals in Note 4 under “Cost-Based Formula Rates with True-Up Mechanism.” Our Regulated Operating Subsidiaries do not earn a return on the balance of these regulatory assets, but do accrue interest carrying costs, which are subject to rate recovery along with the principal amount of the revenue accrual.

[2] Refer to discussion of ITC Great Plains start-up, development and pre-construction in Note 4 under “ITC Great Plains Start-Up, Development and Pre-Construction Regulatory Assets.”