SHARE-BASED COMPENSATION AND EMPLOYEE SHARE PURCHASE PLAN (Details)	6 Months Ended
Jun. 30, 2020 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer Match Contribution	10.00%
Maximum Annual Contribution Percentage of Pay	1.00%
Percent of Dividends Payable	10.00%
2017 Omnibus Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted Award Vesting Rights	The granted awards and related dividend equivalents have no shareholder rights.
2017 Omnibus Plan \| Performance Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted \| shares	288,239
Aggregate fair value of PBUs or SBUs	$ 49,000,000
Total unrecognized compensation cost	$ 20,000,000
2017 Omnibus Plan \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted \| shares	223,082
Aggregate fair value of PBUs or SBUs	$ 27,000,000
Total unrecognized compensation cost	13,000,000
Employee Share Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense (less than $1 million)	$ 1,000,000

ESPP percentage of employer contribution on employee's contribution

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- Definition

Employer maximum annual contribution as a percentage of an employee's base pay

+ References

No definition available.

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- Definition

Dividends payable by Fortis on the Fortis shares allocated to an employee's ESPP account.

+ References

No definition available.

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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

The amount of plan compensation cost recognized during the period.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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- Definition

Description of service or performance condition required to be met for earning right to award under share-based payment arrangement. Includes, but is not limited to, combination of market, performance or service condition.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Net number of non-option equity instruments granted to participants.

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- Definition

Intrinsic value of outstanding award under share-based payment arrangement. Excludes share and unit options.

+ References

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