SUBSEQUENT EVENTS (Details) - Subsequent Event - USD ($)		2 Months Ended
Feb. 09, 2016	Feb. 25, 2016
External Legal, Advisory and Financial Services Fees and Certain Internal Labor and Associated Costs
Subsequent Event
Merger related expenses		$ 10,000,000
ITC Holdings Corp.
Subsequent Event
Cash per common share	$ 22.57
Fortis stock per common share	0.7520
Ownership percentage of Fortis after close of merger	27.00%
Fee for termination of agreement	$ 245,000,000
Fortis Corp.
Subsequent Event
Fee for termination of agreement related to regulatory approvals or matters	$ 280,000,000

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration