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Derivatives Instruments (Derivative Cash Flow Hedges Recorded in Income and AOCI and Notional Volumes of Outstanding Derivatives Designated as Cash Flow Hedges) (Details) $ in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 CAD ($) | Dec. 31, 2019 CAD ($) | Dec. 31, 2020 USD ($)
Cash Flow Hedges |  |  |
Notional volumes of outstanding derivatives designated as cash flow hedges that are expected to settle |  |  | $ 100
Foreign exchange forwards |  |  |
Cash Flow Hedges |  |  |
Total gains (losses) in net income | $ 13 | $ 0 |
Cash flow hedges |  |  |
Cash Flow Hedges |  |  |
Unrealized losses currently in AOCI to be reclassified into net income within the next twelve months | 1 |  |
Cash flow hedges | Interest rate swaps |  |  |
Cash Flow Hedges |  |  |
Total gains (losses) in net income | 0 |  |
Total unrealized gain (loss) in AOCI - effective portion, net of tax | 1 |  |
Cash flow hedges | Interest rate swaps | Regulated |  |  |
Cash Flow Hedges |  |  |
Total gains (losses) in net income | 0 |  |
Cash flow hedges | Interest rate swaps | Power | Non-Regulated |  |  |
Cash Flow Hedges |  |  |
Total unrealized gain (loss) in AOCI - effective portion, net of tax | 0 |  |
Cash flow hedges | Foreign exchange forwards |  |  |
Cash Flow Hedges |  |  |
Total gains (losses) in net income | (2) | (3) |
Total unrealized gain (loss) in AOCI - effective portion, net of tax | 0 | (1) |
Cash flow hedges | Foreign exchange forwards | 2021 |  |  |
Cash Flow Hedges |  |  |
Notional volumes of outstanding derivatives designated as cash flow hedges that are expected to settle |  |  | $ 350
Cash flow hedges | Foreign exchange forwards | Non-Regulated |  |  |
Cash Flow Hedges |  |  |
Total gains (losses) in net income | 0 | 0 |
Cash flow hedges | Foreign exchange forwards | Regulated |  |  |
Cash Flow Hedges |  |  |
Total gains (losses) in net income | $ (2) | $ (3) |

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- Definition Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580 + Details
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- Definition The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994 + Details
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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
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- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
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