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Regulatory Assets and Liabilities - Other Electric Utilities (Narrative) (Details) $ in Millions, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2020 USD ($) | Dec. 31, 2021 | Dec. 31, 2020 CAD ($) | Dec. 31, 2019 CAD ($) | Dec. 31, 2014
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Income tax expense (recovery) |  |  | $ (341) | $ (61) |
Other Electric Utilities | Operating |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Income tax expense (recovery) |  |  | $ 8 | $ (11) |
Barbados Light and Power Company Limited | Other Electric Utilities | Operating |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved regulated return on equity |  |  | 10.00% | 10.00% |
Income tax expense (recovery) | $ 9.6 |  |  |  |
Deferred Tax Liabilities, Regulatory Assets and Liabilities | $ 6.9 |  |  |  |
GBPC | GBPA | Other Electric Utilities | Operating |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved regulated return on equity |  |  | 8.34% | 8.50% |
Recovery Period |  | 5 years |  |  |
GBPC | GBPA | Other Electric Utilities | Operating | Scenario Plan |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved regulated return on equity |  | 8.37% |  |  |
Domlec | Independent Regulatory Commission, Dominica | Other Electric Utilities | Operating |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved regulated return on equity |  |  | 15.00% | 15.00% |
Domlec | Independent Regulatory Commission, Dominica | Other Electric Utilities | Operating | Transmission, Distribution & Supply License and a Generation License |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  | 25 years

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