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Income Taxes (Carry Overs) (Details) - CAD CAD in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Tax Credit Carryforwards | CAD 318 | CAD 7
Tax Loss Carry Forwards Valuation Allowance [Abstract] |  |
Deferred Tax Assets, Valuation Allowance | 58 | 18
Loss carry forwards and investments [Member] |  |
Tax Loss Carry Forwards Valuation Allowance [Abstract] |  |
Deferred Tax Assets, Valuation Allowance | 58 | 18
Domestic Tax Authority [Member] |  |
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Operating Loss Carryforwards | 199 | 103
Deferred Tax Assets, Tax Credit Carryforwards | 0 | 0
Domestic Tax Authority [Member] | Capital Loss Carryforward [Member] |  |
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Operating Loss Carryforwards | 77 | 84
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | 16 |
Valuation Allowance | (16) |
Net Deferred Tax Assets | 0 |
Domestic Tax Authority [Member] | Operating Loss Carryforward [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | 61 |
Valuation Allowance | (27) |
Net Deferred Tax Assets | CAD 34 |
Domestic Tax Authority [Member] | Operating Loss Carryforward [Member] | Maximum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2036 |
Domestic Tax Authority [Member] | Operating Loss Carryforward [Member] | Minimum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2026 |
Foreign Tax Authority [Member] |  |
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Operating Loss Carryforwards | CAD 2,595 | 48
Deferred Tax Assets, Tax Credit Carryforwards | 318 | 30
Foreign Tax Authority [Member] | Capital Loss Carryforward [Member] |  |
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Operating Loss Carryforwards | 14 | 4
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | 3 |
Valuation Allowance | (3) |
Net Deferred Tax Assets | CAD 0 |
Foreign Tax Authority [Member] | Capital Loss Carryforward [Member] | Maximum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2019 |
Foreign Tax Authority [Member] | Capital Loss Carryforward [Member] | Minimum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2018 |
Foreign Tax Authority [Member] | Operating Loss Carryforward [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | CAD 908 |
Valuation Allowance | 0 |
Net Deferred Tax Assets | CAD 908 |
Foreign Tax Authority [Member] | Operating Loss Carryforward [Member] | Maximum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2036 |
Foreign Tax Authority [Member] | Operating Loss Carryforward [Member] | Minimum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2024 |
Foreign Tax Authority [Member] | State Operating Loss Carryforward [Member] |  |
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Operating Loss Carryforwards | CAD 1,183 | 225
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | 45 |
Valuation Allowance | (1) |
Net Deferred Tax Assets | CAD 44 |
Foreign Tax Authority [Member] | State Operating Loss Carryforward [Member] | Maximum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2036 |
Foreign Tax Authority [Member] | State Operating Loss Carryforward [Member] | Minimum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2017 |
Foreign Tax Authority [Member] | Tax credit carry forwards [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | CAD 318 |
Valuation Allowance | 0 |
Net Deferred Tax Assets | CAD 318 |
Foreign Tax Authority [Member] | Tax credit carry forwards [Member] | Maximum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2036 |
Foreign Tax Authority [Member] | Tax credit carry forwards [Member] | Minimum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2019 |
Other Tax Authority [Member] |  |
Tax Loss Carry Forwards [Abstract] |  |
Deferred Tax Assets, Operating Loss Carryforwards | CAD 22 | CAD 14
Other Tax Authority [Member] | Operating Loss Carryforward [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Assets Uncertain Realization | 3 |
Valuation Allowance | (3) |
Net Deferred Tax Assets | CAD 0 |
Other Tax Authority [Member] | Operating Loss Carryforward [Member] | Maximum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2023 |
Other Tax Authority [Member] | Operating Loss Carryforward [Member] | Minimum [Member] |  |
Deferred Tax Assets Uncertain Realization [Abstract] |  |
Deferred Tax Asset Expiration Period | 2017 |

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