Rate of conversion of convertible common stock.

No definition available.

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- Definition

The price per share of the conversion of the debt instrument to common shares.

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
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Balance Type:	na
Period Type:	instant

- Definition

The price per share of the final installment of the conversion of debt instrument to common shares.

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The price per share of the first installment of the conversion of debt instrument to common shares.

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage used to convert debt into common shares.

+ References

No definition available.

+ Details

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- Definition

Additional amount added to the face (par) amount of debt instrument after time of issuance of the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt after tax.

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Proceeds from Convertible Debt , Final Installment

+ References

No definition available.

+ Details

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Namespace Prefix:	ema_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow of the first installment payment from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Proceeds from Convertible Debt Net of Issuance Costs, First Installment

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Conversion Rate
-URI http://asc.fasb.org/extlink&oid=6509012

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

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Balance Type:	na
Period Type:	duration

- Definition

Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Balance Type:	credit
Period Type:	instant

- 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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ 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 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from an obligation which places a lender in a lien position behind debt having a higher priority of repayment (senior loan) in liquidation of the entity's assets scheduled to be repaid within one year or in the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
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-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Stated interest rate of the subordinated debt.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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Common Stock (Narrative) (Details) CAD / shares in Units, shares in Thousands, CAD in Millions			12 Months Ended
	Aug. 02, 2016 CAD CAD / shares	Sep. 28, 2015 CAD CAD / shares	Dec. 31, 2016 CAD NumberOfDays shares	Dec. 31, 2015 CAD	Jun. 30, 2016 CAD	Oct. 02, 2015 CAD
Debt Instrument [Line Items]
Interest Expense, Debt			CAD 443.0	CAD 193.0
Emera Inc \| Convertible Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Convertible, Conversion Per Share \| CAD / shares	CAD 1,000
Debt Instrument, Maturity Date	Sep. 29, 2025
Convertible debenture interest rate	0.00%
Debt Instrument, Convertible, Conversion Ratio	23.8949		0.996
Interest Expense, Debt			CAD 65.0
Interest Expense Debt After Tax			CAD 45.0
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid					CAD 21.0
Debt Instrument Periodic Payment Terms Balloon Payment To Be Paid After Tax					CAD 14.0
Common Stock, Shares, Issued \| shares			51,990
Common Stock, Conversion Rate			95.00%
Debt Instrument, Convertible, Threshold Trading Days \| NumberOfDays			20
TECO Energy Inc [Member] \| Emera Inc \| Convertible Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		CAD 1,900.0
Debt Instrument, Convertible, Conversion Percent		4.00%
Debt Instrument, Face Amount, Additional Amount						CAD 285.0
Aggregate proceeds of the Debenture Offering		CAD 2,185.0
Debt Instrument, Convertible, Conversion Per Share \| CAD / shares		CAD 1,000
Debt Instrument, Convertible, Conversion Per Share, First Installment \| CAD / shares		CAD 333
Debt Instrument, Convertible, Conversion Per Share, Final Installment \| CAD / shares	CAD 667
Proceeds from Convertible Debt First Installment		CAD 727.6
Proceeds from Convertible Debt Net of Issuance Costs, First Installment	CAD 1,413.0	CAD 681.4
Proceeds from Convertible Debt , Final Installment	CAD 1,457.0
Debt Instrument, Convertible, Conversion Price \| CAD / shares	CAD 41.85