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Income Taxes (Narrative) (Details) - CAD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
Entity [Domain] |  |
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] |  |
Temporary Differences/Potential change | $ 1,900 | $ 1,400
2005 and subsequent years | Entity [Domain] |  |
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] |  |
Open Tax Year | 2005 |
Settlement with Taxing Authority | 2006 through 2010 years | Nova Scotia Power Inc. | Canada Revenue Agency |  |
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] |  |
Net amount in dispute | $ 62 |
Prepaid amount in dispute | $ 23 |

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