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Commitments and Contingencies (Legal Proceedings) (Details) - 12 months ended Dec. 31, 2017 $ in Millions, $ in Millions	USD ($)	CAD ($)	USD ($)
Tampa Electric And Peoples Gas Division [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		$ 38	$ 30
Emera Maine [Member] | ISO New England OATT [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 4
TECO Guatemala Holdings [Member] | Prime Rate [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount	$ 21

X

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

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X

- 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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X

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

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- Details

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X

- Details

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X

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