Advances against the line of credit facility which can be made by way of overdraft.

No definition available.

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

- Definition

Amount of borrowed funds under the facility.

+ References

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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

Name:	us-gaap_ShortTermDebtLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of short-term debt outstanding.

+ References

+ Details

Name:	us-gaap_ShortTermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=ema_ShortTermDebtRevolvingAndNonRevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ema_TecoEnergyIncAndTecoFinanceIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=ema_FinanceTermCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ema_TampaElectricDivisionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ema_NewMexicoGasCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ema_GrandBahamaPowerCompanyLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ema_EmeraEnergyServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Short Term Debt (short-term revolving and non-revolving credit facilities, outstanding borrowings and available capacity) (Details) - CAD CAD in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 13, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 1,762		CAD 18
Letters of Credit Outstanding, Amount		CAD 37	33
Total advances under available facilities		363	674
Available capacity under existing agreements		1,070	663
Long-term Line of Credit		CAD 326	CAD 641
Short-term Debt, Weighted Average Interest Rate	1.73%		2.70%
Short term debt revolving and non revolving credit facility [Member]
Short-term Debt [Line Items]
Credit Facility Advances	CAD 960		CAD 0
Letters of Credit Outstanding, Amount	3		0
Total advances under available facilities	963		0
Available capacity under existing agreements	799		18
TECO Energy Inc. and TECO Finance Inc. [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 403		CAD 0
Line of Credit Facility, Expiration Date	Dec. 31, 2018
TECO Energy Inc. and TECO Finance Inc. [Member] \| Line of Credit [Member]
Short-term Debt [Line Items]
Short-term Debt, Weighted Average Interest Rate	1.74%		0.00%
TECO Energy Inc. and TECO Finance Inc. [Member] \| Finance Term Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 537		CAD 0
Line of Credit Facility, Expiration Date	Dec. 31, 2017
Tampa Electric Division [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 436		0
Line of Credit Facility, Expiration Date	Dec. 31, 2018
Tampa Electric Division [Member] \| Accounts Receivable Revolving Credit Facility
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 201		CAD 0
Line of Credit Facility, Expiration Date	Dec. 31, 2018
Tampa Electric Division [Member] \| Line of Credit [Member]
Short-term Debt [Line Items]
Short-term Debt, Weighted Average Interest Rate	1.49%		0.00%
New Mexico Gas Company [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 168		CAD 0
Line of Credit Facility, Expiration Date	Dec. 31, 2018
New Mexico Gas Company [Member] \| Line of Credit [Member]
Short-term Debt [Line Items]
Short-term Debt, Weighted Average Interest Rate	1.71%		0.00%
Grand Bahama Power Company Limited [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 17		CAD 18
Line of Credit Facility, Expiration Date	Dec. 31, 2017
Emera Energy Services [Member] \| Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	CAD 0		CAD 0
Line of Credit Facility, Expiration Date	Dec. 31, 2014
Short-term Debt, Weighted Average Interest Rate	0.00%		0.00%