Long-Term Debt - Schedule of Long-Term Debt (Details) - CAD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt, excluding credit facility borrowings	$ 23,656	$ 21,547
Long-term debt	24,698	22,320
Less: Deferred financing costs and debt discounts	(147)	(129)
Less: Current installments of long-term debt	(990)	(690)
Long-term debt less current portion and deferred financing costs and debt discounts	23,561	21,501
ITC
Debt Instrument [Line Items]
Fair value adjustment - ITC acquisition	133	133
Credit facility
Debt Instrument [Line Items]
Long-term debt	909	640
Less: Current installments of long-term debt	(371)	(252)
Credit facility \| Long-term credit facility borrowings
Debt Instrument [Line Items]
Long-term debt	$ 909	$ 640

Fair Value, Debt Instrument, Valuation Adjustment

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- Definition

Long-Term Debt Excluding Credit Facilities

+ References

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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Amount of unamortized debt discount (premium) and debt issuance costs.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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