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Regulatory Assets and Liabilities (Emera Maine ) (Details) CAD in Millions, $ in Millions |  |  |  |  |  | 1 Months Ended | 6 Months Ended | 12 Months Ended | 15 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 21, 2016 CAD | Jun. 01, 2016 | Jan. 02, 2015 | Jun. 19, 2014 | Sep. 30, 2011 | Oct. 31, 2016 USD ($) Transmissions_Distribution_Poles | Jun. 30, 2016 | Dec. 31, 2016 CAD km | Dec. 31, 2015 CAD | Mar. 31, 2014 | Dec. 31, 2012
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  | CAD 1,322.0 | CAD 699.0 |  |
Emera Maine [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  | 10.57% | 11.14% |  | 10.57% |  |  | 10.57% | 11.74%
Emera Maine [Member] | Restructuring Of Above-market Power Purchase Contract And Deferrals [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net Regulatory Assets |  |  |  |  |  |  |  | CAD 11.4 |  |  |
Net Regulatory Assets, Percentage |  |  |  |  |  |  |  | 1.00% |  |  |
Emera Maine [Member] | Maine Public Utilities Commission (MPUC) [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage | 9.00% |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Equity Capital Structure, Percentage | 49.00% |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Percentage | 3.75% |  |  |  |  |  |  |  |  |  |
Emera Maine [Member] | Maine Public Utilities Commission (MPUC) [Member] | Storm Costs [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount | CAD 4.0 |  |  |  |  |  |  |  |  |  |
Bangor Hydro District [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Percentage |  | 2.00% |  |  |  |  |  |  | 21.00% |  |
Public Utilities, Recoverable Transmission Investment and Expenses, Percentage |  | 9.00% |  |  |  |  |  |  | (6.00%) |  |
Bangor Hydro District [Member] | Restructuring Of Above-market Power Purchase Contract And Deferrals [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net Regulatory Assets |  |  |  |  |  |  |  |  | CAD 19.7 |  |
Net Regulatory Assets, Percentage |  |  |  |  |  |  |  |  | 1.80% |  |
Maine Public Service District [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  | 6.75% |  |  |  |  |  |  |  |
Public Utilities, Approved Equity Capital Structure, Percentage |  |  | 48.00% |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Percentage |  | 10.20% |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Retail Customers, Percentage |  | 36.00% |  |  |  |  |  |  | (22.00%) |  |
Public Utilities, Requested Rate Increase (Decrease), Wholesale Customers, Percentage |  | 43.00% |  |  |  |  |  |  | (1.00%) |  |
Barbados Light & Power Company Limited [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  | 10.00% | 10.00% |  |
Dominica Electricity Services Ltd. [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  | 15.00% | 15.00% |  |
Grand Bahama Power Company Limited [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  | 8.80% | 10.00% |  |
Regulatory Assets | $ |  |  |  |  |  | $ 21 |  |  |  |  |
Property plant and equipment | $ |  |  |  |  |  | $ 7 |  |  |  |  |
Regulatory Asset Amortization Period |  |  |  |  |  | 5 years |  |  |  |  |
Property plant and equipment useful life |  |  |  |  |  | 27 years |  |  |  |  |
Grand Bahama Power Company Limited [Member] | Storm Costs [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of Transmission and Distribution Poles | Transmissions_Distribution_Poles |  |  |  |  |  | 2,100 |  |  |  |  |
Public Utilities Restoration Cost | $ |  |  |  |  |  | $ 28 |  |  |  |  |
Brunswick Pipeline [Member] |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Length Of Pipeline | km |  |  |  |  |  |  |  | 145 |  |  |

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