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v3.20.4

Income Taxes - Narratives (Details) - CAD ($) | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Provisions [Line Items] |  |
Corresponding increase in tax expense | $ (5,028,000) | $ 8,747,000
Letters of credit oustanding | 1,596,488,000 | $ 1,528,603,000
Canadian Revenue Agency [member] |  |
Provisions [Line Items] |  |
Amount of potential taxable income consequences from tax dispute | $ 6,600,000,000 |
Percentage of taxes and interest charges | 50.00% |
Penalties related to transfer pricing [member] | Canadian Revenue Agency [member] |  |
Provisions [Line Items] |  |
Provision for CRA transfer price dispute | $ 371,000,000 |
Provision for uncertain tax positions [member] | Canadian Revenue Agency [member] |  |
Provisions [Line Items] |  |
Corresponding increase in tax expense | 2,600,000,000 |
Provision for uncertain tax positions [member] | Canadian Revenue Agency [member] | Bottom of range [member] |  |
Provisions [Line Items] |  |
Amount of potential taxable income consequences from tax dispute | 6,600,000,000 |
Provision for uncertain tax positions [member] | Canadian Revenue Agency [member] | Top of range [member] |  |
Provisions [Line Items] |  |
Amount of potential taxable income consequences from tax dispute | 8,700,000,000 |
Provision for uncertain tax positions [member] | Penalties related to cash taxes and transfer pricing [member] | Canadian Revenue Agency [member] | Bottom of range [member] |  |
Provisions [Line Items] |  |
Provision for CRA transfer price dispute | 1,950,000,000 |
Provision for uncertain tax positions [member] | Penalties related to cash taxes and transfer pricing [member] | Canadian Revenue Agency [member] | Top of range [member] |  |
Provisions [Line Items] |  |
Provision for CRA transfer price dispute | 2,150,000,000 |
Provision for uncertain tax positions [member] | 50% Penalties related to cash tax and transfer pricing [member] | Canadian Revenue Agency [member] | Bottom of range [member] |  |
Provisions [Line Items] |  |
Provision for CRA transfer price dispute | 970,000,000 |
Provision for uncertain tax positions [member] | 50% Penalties related to cash tax and transfer pricing [member] | Canadian Revenue Agency [member] | Top of range [member] |  |
Provisions [Line Items] |  |
Provision for CRA transfer price dispute | $ 1,070,000,000 |

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