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Income Taxes (Net operating loss, capital loss and tax credit carryforwards and their expiration periods) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2020 CAD ($)
Canada | Capital loss |
Composition of taxes on income from continuing operations [Line items] |
Gross Tax Carryforwards | $ 61
Unrecognized Amounts | (61)
Net Tax Credit Carryforwards | $ 0
Expiration period | Indefinite
Canada | NOL |
Composition of taxes on income from continuing operations [Line items] |
Gross Tax Carryforwards | $ 1,370
Unrecognized Amounts | (619)
Net Tax Credit Carryforwards | $ 751
Expiration period | 2027 - 2040
United States | NOL |
Composition of taxes on income from continuing operations [Line items] |
Gross Tax Carryforwards | $ 1,412
Unrecognized Amounts | 0
Net Tax Credit Carryforwards | $ 1,412
Expiration period | 2030 - 2040
United States | Tax credit |
Composition of taxes on income from continuing operations [Line items] |
Gross Tax Carryforwards | $ 319
Unrecognized Amounts | 0
Net Tax Credit Carryforwards | $ 319
Expiration period | 2025 - 2040
State | NOL |
Composition of taxes on income from continuing operations [Line items] |
Gross Tax Carryforwards | $ 563
Unrecognized Amounts | 0
Net Tax Credit Carryforwards | $ 563
Expiration period | 2032 - 2040
Other | NOL |
Composition of taxes on income from continuing operations [Line items] |
Gross Tax Carryforwards | $ 39
Unrecognized Amounts | (39)
Net Tax Credit Carryforwards | $ 0
Expiration period | 2021 - 2027

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- Definition The amount of net tax credit carryforward, available to reduce future taxable income under enacted tax laws. + References No definition available. + Details
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- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319 + Details
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- Definition Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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