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Non-controlling Interest In Subsidiaries (Preferred Shares Authorized) (Details) - CAD CAD in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Noncontrolling Interest [Line Items]
Number of shares issued and outstanding	29,000,000	29,000,000
Nova Scotia Power Inc. [Member]
Noncontrolling Interest [Line Items]
Preferred Stock, Shares Authorized, Unlimited	Unlimited
Number of shares issued and outstanding	0	0
Preferred Stock Value Outstanding	CAD 0.0	CAD 0.0
Grand Bahama Power Company Limited [Member] | Non-voting Cumulative Redeemable Variable Perpetual Preferred Shares [Member]
Noncontrolling Interest [Line Items]
Preferred Stock, Shares Authorized	35,000,000,000
Number of shares issued and outstanding	35,000,000,000	35,000,000,000
Preferred Stock Value Outstanding	CAD 34.0	CAD 34.0

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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

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Indicates that the number of nonredeemable preferred shares, or preferred stock redeemable solely at the option of the issuer, permitted to be issued by an entity's charter and bylaws is unlimited. The acceptable value is "Unlimited".

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.28)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Value of all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by shareholders, which is net of related treasury stock. May be all or a portion of the number of preferred shares authorized. These shares represent the ownership interest of the preferred shareholders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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