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Investments Subject to Significant Influence and Equity Income (Equity Method) (Details) - Entity [Domain] - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2015
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | $ 1,346 | $ 1,312 |
Equity Method Investment, Summarized Financial Information [Abstract] |  |  |
Other long-term liabilities | 781 | 764 |
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity | 12 |  |
Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | 1,346 | 1,312 |
Income (loss) from equity investments and subsidiaries | 149 | 154 |
Equity Method Investment, Summarized Financial Information [Abstract] |  |  |
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity | 12 |  |
NSPML | Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | 547 | 554 |
Income (loss) from equity investments and subsidiaries | $ 47 | 46 |
Percentage of Ownership | 100.00% |  |
LIL | Class B units |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Percentage of Ownership | 100.00% |  |
LIL | Total Units Issued [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Percentage of Ownership | 24.90% |  |
LIL | Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | $ 629 | 579 |
Income (loss) from equity investments and subsidiaries | $ 49 | 45 |
Percentage of Ownership | 45.60% |  |
M&NP | Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | $ 129 | 138 |
Income (loss) from equity investments and subsidiaries | $ 20 | 22 |
Percentage of Ownership | 12.90% |  |
Lucelec | Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | $ 41 | 41 |
Income (loss) from equity investments and subsidiaries | $ 4 | 3 |
Percentage of Ownership | 19.50% |  |
Bear Swamp |  |  |
Equity Method Investment, Summarized Financial Information [Abstract] |  |  |
Distribution received |  |  | $ 179
Other long-term liabilities | $ 118 | 137 |
Bear Swamp | Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | 0 | 0 |
Income (loss) from equity investments and subsidiaries | $ 29 | 35 |
Percentage of Ownership | 50.00% |  |
Other Investments | Equity Method Investee | Emera Inc. |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investments subject to significant influence | $ 0 | 0 |
Income (loss) from equity investments and subsidiaries | $ 0 | $ 3 |
Maritime Link And LIL | Plan, subject to approval |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Percentage of Ownership | 49.00% |  |

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- Definition Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
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