Schedule of Notes Payable Schedule of Short-Term Debt [Table Text Block] Commodities Commodity contracts Commodity Contract [Member] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Schedule of Estimated Future Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Senior Unsecured Notes due October 2031 Senior Unsecured Notes Due October 2031 [Member] Senior Unsecured Notes Due October 2031 Shares issued: Shares Issued [Abstract] Shares Issued [Abstract] Entity File Number Entity File Number Additional Paid-In Capital Additional Paid-in Capital [Member] Investments of regulated natural gas pipelines (in kilometers) Public Utilities, Property, Plant and Equipment, Regulated Natural Gas Pipelines, in Kilometers Public Utilities, Property, Plant and Equipment, Regulated Natural Gas Pipelines, in Kilometers Target Allocations Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Other Comprehensive Income (Loss) Other Comprehensive Income (Loss), Tax Accounting Changes New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Potential Exposure Guarantor Obligations, Maximum Exposure, Undiscounted Fixed percentage added to government of Canada bond or treasury bill rate, for calculating dividend yield per annum (as a percent) Preferred Stock Fixed Percentage Added to Bond or Treasury Bill Rate for Calculating Dividend Yield Represents the fixed percentage added to bond yield or treasury bill rate, for calculating dividend yield per annum. Income Tax (Expense) Recovery Other Comprehensive Income (Loss), Tax [Abstract] Unrealized Foreign Exchange on Long-Term Debt Valuation Allowance, Unrealized Foreign Exchange On Long-Term Debt Valuation Allowance, Unrealized Foreign Exchange On Long-Term Debt Goodwill recorded on Company's acquisitions in the U.S. Goodwill [Line Items] Position [Axis] Position [Axis] Canada – domestic Canada Domestic [Member] Represents information pertaining to the domestic revenues of the entity by geographic region. Measurement Basis [Axis] Measurement Basis [Axis] Other Other Assets, Miscellaneous, Current REVENUES Revenue from Contract with Customer [Text Block] Unsecured Term Loan Due October 2028 Unsecured Term Loan Due October 2028 [Member] Unsecured Term Loan Due October 2028 Unanimous negotiated settlement period Unanimous Negotiated Settlement Period Unanimous Negotiated Settlement Period Debt Instrument Interest Rate Period [Axis] Debt Instrument Interest Rate Period [Axis] Debt Instrument Interest Rate Period [Axis] Dividends on preferred shares Payments of Ordinary Dividends, Preferred Stock and Preference Stock Stock, Class of Stock [Table] Stock, Class of Stock [Table] Joint venture Corporate Joint Venture [Member] Other Other Long-Lived Tangible Assets [Member] Other Long-Lived Tangible Assets Continuing Operations Continuing Operations [Member] RISK MANAGEMENT AND FINANCIAL INSTRUMENTS Derivatives and Fair Value [Text Block] Current Total Current Income Tax Expense (Benefit) Other Other Assets, Miscellaneous, Noncurrent Long-Term Assets of Discontinued Operations (Note 4) Disposal Group, Including Discontinued Operation, Assets Schedule of Regulatory Assets and Liabilities Schedule of Regulatory Assets and Liabilities [Table Text Block] Tabular disclosure of the assets and liabilities that are created when regulatory agencies permit public utilities to defer certain costs that are included in rate-setting to the balance sheet. Pension Benefit Plans Pension Plan [Member] Medium Term Notes Due October 2024 Medium Term Notes Due October 2024 2 [Member] Medium Term Notes Due October 2024 2 Unamortized debt discount and issue costs Unamortized debt issue costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Restricted Interest and Financing Expense Restricted Interest and Financing Expense, Carryforwarda Restricted Interest and Financing Expense, Carryforwarda Schedule of Plan Assets for DB Plans and Other Post-Retirement Benefits Measured at Fair Value Schedule of Fair Value of Plan Assets [Table Text Block] Tabular disclosure of the fair value of each major category of plan assets, and the level within the fair value hierarchy in which the fair value measurements fall. Impairment losses pre tax Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, before Tax, Portion Attributable to Parent TCPL / TCPL USA TCPL, TCPL USA [Member] TCPL, TCPL USA Amount to be addressed In next settlement Contingent Liability, Regulated Liability Balance Settlement, Amount to Be Addressed In Next Settlement Contingent Liability, Regulated Liability Balance Settlement, Amount to Be Addressed In Next Settlement Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Interest and Financing Expense Restricted Interest and Financing Expense, Valuation Allowance Restricted Interest and Financing Expense, Valuation Allowance Percentage Effective Income Tax Rate Reconciliation, Percent [Abstract] Percentage level to which average annual rate was assumed to decrease Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Cost for facilities accounted for as operating leases Property, Plant, and Equipment, Lessor Asset under Operating Lease, before Accumulated Depreciation Controlling Interests Equity, Attributable to Parent Measurement Frequency [Axis] Measurement Frequency [Axis] Other Comprehensive Income (Loss), Net of Tax Net of Tax Amount Other Comprehensive Income (Loss), Net of Tax [Abstract] Schedule of Plant, Property and Equipment Property, Plant and Equipment [Table Text Block] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Adjustments Hedged Liability, Fair Value Hedge, Adjustments Hedged Liability, Fair Value Hedge, Adjustments Contributions to equity method investments Payments To Acquire Productive Assets, Excluding Discontinued Operations Payments To Acquire Productive Assets, Excluding Discontinued Operations Recurring basis Fair Value, Recurring [Member] Non-controlling interests Noncontrolling Interest [Line Items] Pre tax separation, before reclassification, after tax Spinoff Transaction, Separation Transaction Costs, Net of Tax Spinoff Transaction, Separation Transaction Costs, Net of Tax Senior Unsecured Notes due October 2023 Senior Unsecured Notes Due October 2023 [Member] Senior Unsecured Notes Due October 2023 Summarized cash flows information for Discontinued operations [Abstract] Cash Provided by (Used in) Discontinued Operation [Abstract] LIABILITIES Liabilities and Equity [Abstract] Medium Term Notes Medium-Term Note [Member] Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 4 [Member] Senior Unsecured Notes Due October 2024 4 Cover [Abstract] Renewable Power Generation Renewable Power Generation [Member] Renewable Power Generation Solar Generation Solar Generation [Member] Solar Generation Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] DISCONTINUED OPERATIONS Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Maximum Maximum [Member] Net income (loss) attributable to non-controlling interests (Note 22) Net income (loss) attributable to non-controlling interests (Note 22) Net (income) loss attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Senior Unsecured Notes Due August 2026 Senior Unsecured Notes Due August 2026 [Member] Senior Unsecured Notes Due August 2026 Accrued interest expense Unrecognized Tax Benefits, Interest on Income Taxes Accrued NGTL System NGTL System [Member] NGTL System [Member] Financing receivable, recorded investment, past due Accounts Receivable, Past Due, Amount Accounts Receivable, Past Due, Amount Unrealized gains (losses) attributed to derivatives in the Level III category Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss) $500 notes due 2081 at 4.45% Junior Subordinated Notes Due 2081 [Member] Junior Subordinated Notes Due 2081 Debt Instrument [Line Items] Debt Instrument [Line Items] Other Restricted Investments Other Restricted Investments [Member] Other Restricted Investments [Member] Notional amount Debt, Long-Term and Short-Term, Combined Amount Power generation Power Generation [Member] Power Generation [Member] Accounts payable and other Disposal Group, Including Discontinued Operation, Accounts Payable, Current Junior subordinated debt, due 2075 Junior Subordinated Debt, Due 2075 [Member] Junior Subordinated Debt, Due 2075 [Member] Employee Post-Retirement Benefits Retirement Benefits [Abstract] Long-Term Liabilities of Discontinued Operations (Note 4) Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent Income (Loss) from Continuing Operations before Income Taxes Income before income taxes Total before tax Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Common Stock, Number of Shares, Par 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non-controlling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Noncontrolling interest acquired Business Acquisition, Noncontrolling Interest Acquired, Amount Business Acquisition, Noncontrolling Interest Acquired, Amount Asset Retirement Obligations Asset Retirement Obligation [Policy Text Block] Short-term Debt [Abstract] Short-Term Debt [Abstract] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Schedule of Other Current Assets Schedule of Other Current Assets [Table Text Block] Net income (loss) attributable to controlling interests from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Canada Income (Loss) from Continuing Operations before Income Taxes, Domestic Operating lease, reported as accounts payable and other Operating lease liabilities (Note 9) Operating Lease, Liability, Current Capital expenditure commitment Capital Expenditure Commitment Capital Expenditure Commitment Document Fiscal Period Focus Document Fiscal Period Focus Disposition of equity interest, net of transaction costs (Note 29) Proceeds from Disposition of Noncontrolling Interests Proceeds from Disposition of Noncontrolling Interests Rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Loans and Receivables Receivable [Policy Text Block] Property taxes Real Estate Tax Expense Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] USA TransCanada American Investments, Ltd., and TransCanada Power Marketing Ltd. [Member] TransCanada American Investments, Ltd., and TransCanada Power Marketing Ltd. [Member] Other equity investments Pipeline Equity Investments And Other [Member] Pipeline Equity Investments And Other Property taxes Disposal Group, Including Discontinued Operation, Property Taxes Disposal Group, Including Discontinued Operation, Property Taxes Continuing operations, Diluted (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Hedging Relationship [Domain] Hedging Relationship [Domain] Currency Translation Adjustments Currency translation adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Two to three years Sales-Type and Direct Financing Leases, Payment to be Received, Year Three Medium Term Note Due July 2023 Medium Term Note Due July 2023 [Member] Medium Term Note Due July 2023 Investment, Name [Domain] Investment, Name [Domain] Stock Options and Other Compensation Programs Share-Based Payment Arrangement [Policy Text Block] Trading Symbol Trading Symbol Three to four years Lessee, Operating Lease, Liability, to be Paid, Year Four Comprehensive Income (Loss) Attributable to Common Shares Comprehensive Income (Loss), Net of Tax, Attributable to Common Shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Common Shareholders Stated interest rate, period of time after first term Debt Instrument, Interest Rate, Stated Percentage, Period Of Time, After Initial Term Debt Instrument, Interest Rate, Stated Percentage, Period Of Time, After Initial Term Auditor Information [Abstract] Auditor Information Changes in valuation allowances Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Entity Address, City or Town Entity Address, City or Town Financial instruments Deferred Tax Liabilities, Interests in Financial Assets Continued to be Held Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Gain (Loss) on Investments, Realized and Unrealized Debt Securities, Available-for-Sale, Gain (Loss) [Abstract] Medium-Term Notes, Maturity Date of 2026 Medium-Term Notes, Maturity Date of 2026 [Member] Medium-Term Notes, Maturity Date of 2026 [Member] Effect of Foreign Exchange Rate Changes on Cash and Cash Equivalents Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Foreign exchange rate changes Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) TC Energy and South Bow TC Energy And South Bow [Member] TC Energy And South Bow Deferred tax assets, net of Valuation allowance Deferred Tax Assets, Net of Valuation Allowance Notes payable issued (repaid), net Proceeds from (Repayments of) Short-Term Debt Statement of Income Location, Balance [Domain] Statement of Income Location, Balance [Domain] TQM Trans Quebec and Maritimes Pipeline Inc [Member] Represents information pertaining to Trans Quebec and Maritimes Pipeline Inc. Expected average remaining life expectancy of former employees over which past service costs are amortized Post-retirement and Post-employment Plans, Expected Average Remaining Life Expectancy of Former Employees Represents the expected average remaining life expectancy of employees for amortization of past service costs under postretirement and postemployment plans. Spinoff of Liquids Pipelines business (in shares) Stockholders' Equity Note, Spinoff Transaction, Shares Stockholders' Equity Note, Spinoff Transaction, Shares Settlement Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities TC Energy TC Energy [Member] TC Energy Entity Emerging Growth Company Entity Emerging Growth Company 2028 Long-Term Debt, Maturity, Year Three Net loss (gain) Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Cash collateral provided by the Company Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Great Lakes Great Lakes [Member] Represents information pertaining to a natural gas transmission system that connects to the Canadian Mainline and serves markets in eastern Canada and the northeastern and Midwestern United States (U.S.). Outstanding at the beginning of the period (in shares) Outstanding at the end of the period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Realized gains (losses) in the year Derivative, Gain (Loss) on Derivative, Net 2026 Defined Benefit Plan, Expected Future Benefit Payment, Year One Taxes on future revenue requirement Deferred Tax Liabilities, Tax Deferred Income Fixed Income Securities, Canadian Bonds, Corporate Debt Security, Corporate, Canada [Member] Debt Security, Corporate, Canada [Member] Derivative instruments held for trading (Note 27) Derivative Instrument Held-For-Trading [Member] Derivative Instrument Held-For-Trading Common shares outstanding (in shares) Outstanding at the beginning of the period (in shares) Outstanding at the end of the period (in shares) Common Stock, Shares, Outstanding Expected credit loss provision Sales-type Lease, Currency Translation Loss Sales-type Lease, Currency Translation Loss Fair Value Net Derivative Asset (Liability) Measured on Recurring Basis Unobservable Input Reconciliation [Table] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Weighted average actuarial assumptions adopted in measuring the benefit obligations Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Change in fair value of net investment hedges Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease) Pre-tax amounts recognized in OCI Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] LOANS WITH AFFILIATES Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Schedule of Disaggregation of Revenues Disaggregation of Revenue [Table Text Block] Options Exercisable at December 31, 2025 Share-Based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Remaining Contractual Term Schedule of Common Shares Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Other Other Regulatory Assets [Member] Represents the regulatory assets arising from other regulatory matters not specified in the taxonomy. Bruce Power Bruce Power [Member] Represents information pertaining to nuclear power generation facilities of Bruce A and Bruce B collectively referred as Bruce Power. Series 4 Series Four Preferred Stock [Member] Represents information pertaining to the Series 4 cumulative preferred stock. Employee post-retirement benefits (Note 26) Other long-term assets (Note 14) Assets for Plan Benefits, Defined Benefit Plan Income Tax Expense (Recovery) from Continuing Operations (Note 18) Current Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Income tax liabilities Accrued Income Taxes, Current Junior subordinated debt, due 2067 Junior Subordinated Debt, Due 2067 [Member] Junior Subordinated Debt, Due 2067 [Member] Exercise of stock options Exercise of options Stock Issued During Period, Value, Stock Options Exercised Carrying Value Guarantor Obligations, Current Carrying Value Schedule of Long-Lived Assets by Country Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block] Proceeds from sale of equity Proceeds from Issuance or Sale of Equity Change in Benefit Obligation Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Funded Status – Plan Surplus Defined Benefit Plan, Accumulated Benefit Obligation Less Fair Value of Plan Assets The difference between the accumulated benefit obligation and fair value of plan assets. Discontinued operations, Diluted (in dollars per share) Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share Interest rate Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Entity Address, Postal Zip Code Entity Address, Postal Zip Code Expected average remaining service life of employees over which past service costs are amortized Defined Benefit Plan, Expected Average Remaining Service Life of Employees over which Past Service Costs Amortized Represents the expected average remaining service life of employees for amortization of past service costs under the defined benefit plans. Income Tax Expense Income tax (expense) recovery from continuing operations Income tax (expense) recovery Income Tax Expense (Benefit) Common Class B Common Class B [Member] Canada - provincial Income Tax Paid, Provincial, after Refund Received Income Tax Paid, Provincial, after Refund Received Emissions credits Emission Credits Emission Credits Derivative instruments in hedging relationships Designated as Hedging Instrument [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Schedule of Weighted Average Assumptions Used in Calculating Benefit Obligation Schedule of Weighted Average Assumptions Used in Calculating Benefit Obligation [Table Text Block] Schedule of Weighted Average Assumptions Used in Calculating Benefit Obligation [Table Text Block] Hedging Relationship [Axis] Hedging Relationship [Axis] Long-term Purchase Commitment [Table] Long-Term Purchase Commitment [Table] Cost Property, Plant and Equipment, Gross Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets for All DB Plans Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Table Text Block] Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations and Disposal Groups [Abstract] Retirement Plan Funding Status [Domain] Defined Benefit Plan, Funding Status [Domain] (Increase) decrease in Other current assets Increase (Decrease) in Other Current Assets Senior Unsecured Term Loan Due January 2028 Senior Unsecured Term Loan Due January 2028 [Member] Senior Unsecured Term Loan Due January 2028 Savings and DC Plans Defined Contribution Plan, Employer Discretionary Contribution Amount Guarantor Obligation [Table] Guarantor Obligation [Table] ACQUISITIONS AND DISPOSITIONS Mergers, Acquisitions and Dispositions Disclosures [Text Block] Acquisitions, net of cash acquired (Note 29) Payments to Acquire Businesses, Net of Cash Acquired Source allocation percentage Derivative, Source Allocation, Percentage Derivative, Source Allocation, Percentage Canada - federal Income Tax Paid, Federal, after Refund Received Pensions and other post retirement benefits Pension and Other Postretirement Plans Costs [Member] Redemption price as a percentage of principal amount plus accrued and unpaid interest Debt Instrument, Redemption Price, Percentage North Baja North Baja Pipeline, LLC [Member] North Baja Pipeline, LLC [Member] Operating losses Deferred Tax Assets, Operating Loss Carryforwards, Domestic Preferred share dividends Preferred share dividends Preferred share dividends Preferred Stock Dividends, Income Statement Impact Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Discontinued operations Payments to Acquire Oil and Gas Property and Equipment, Discontinued Operation Payments to Acquire Oil and Gas Property and Equipment, Discontinued Operation Capital expenditures (Note 5) Payments to Acquire Oil and Gas Property and Equipment Consideration received as a reduction to additional paid in capital Payments To Acquire Equity Method Investments, Noncontrolling Interest Distribution,, Net of Tax Payments To Acquire Equity Method Investments, Noncontrolling Interest Distribution,, Net of Tax Unrecognized compensation costs related to non-vested stock options Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount Foreign federal and state operating losses Deferred Tax Assets, Operating Loss Carryforwards, Foreign Net cash provided by operations Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Amounts recognized in the Balance Sheet Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract] Portland Natural Gas Transmission System Portland Natural Gas Transmission System [Member] Represents information pertaining to Portland, a natural gas transmission system that extends from a point near East Hereford, Quebec, to the northeastern U.S. Effective Income Tax Rate Reconciliation [Table] Effective Income Tax Rate Reconciliation [Table] Non-lease components Non-Lease Components [Member] Non-Lease Components Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] South Bow Canadian Infrastructure Holdings Ltd South Bow Canadian Infrastructure Holdings Ltd [Member] South Bow Canadian Infrastructure Holdings Ltd Subsequent event Subsequent Event [Member] Schedule of Options Valuation Assumptions Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Number of Shares Common Shares Disclosure [Roll Forward] Common Shares Disclosure Group of Investees Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Equity Investments Schedule of Equity Method Investments [Line Items] Denominated value Liability, Reporting Currency Denominated, Value Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Other Other Instruments [Member] Other Instruments Derivative Liabilities Derivative Instrument Liabilities Derivative Liability, Subject to Master Netting Arrangement, before Offset Medium Term Notes Due July 2030 Medium Term Notes Due July 2030 [Member] Medium Term Notes Due July 2030 Senior Unsecured Notes Due August 2030 Senior Unsecured Notes Due August 2030 [Member] Senior Unsecured Notes Due August 2030 Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Sublease income Sublease Income Loans and Leases Receivable Disclosure [Table] Loans and Leases Receivable Disclosure [Table] Number of reportable segments (in segments) Number of Reportable Segments Interest allocated to discontinued operations Interest Paid, Discontinued Operations Revenue Sales [Member] DB Plans and Other post-retirement benefit plans Defined Benefit Plan, Cash Contributions By Employer Defined Benefit Plan, Cash Contributions By Employer Capital expenditures Capital Payments to Acquire Oil and Gas Property and Equipment, Excluding Discontinued Operations Capital Payments to Acquire Oil and Gas Property and Equipment, Excluding Discontinued Operations Valuation Allowance Deferred Tax Assets, Net of Valuation Allowance [Abstract] VARIABLE INTEREST ENTITIES Variable Interest Entity Disclosure [Text Block] CHANGES IN OPERATING WORKING CAPITAL Changes in Operating Working Capital Disclosure [Text Block] The entire disclosure for changes in operating working capital. Entity Address, Country Entity Address, Country Regulatory Liabilities (Note 12) Regulatory liabilities, noncurrent Regulatory Liabilities Regulatory Liability, Noncurrent Entity Address, State or Province Entity Address, State or Province More than five years Sales-Type and Direct Financing Leases, Payment to be Received, after Year Five Common share dividends Dividends, Common Stock Long-Term Assets of Discontinued Operations (Note 4) Disposal Group, Including Discontinued Operation, Assets, Noncurrent 2029 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Unused borrowing capacity, amount Debt Instrument, Unused Borrowing Capacity, Amount Total current liabilities Current liabilities Liabilities, Current Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-Term Purchase Commitment, Category of Item Purchased [Domain] Medium Term Notes Due October 2024 Medium Term Notes Due October 2024 1 [Member] Medium Term Notes Due October 2024 1 Expense for savings plan and DC Plans Defined Contribution Plan, Cost Income Tax Jurisdiction [Domain] Income Tax Jurisdiction [Domain] Gross decrease - tax positions in current year Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions Accounting Changes and Error Corrections [Abstract] Accounting Changes and Error Corrections [Abstract] Dividends on common shares Payments of Ordinary Dividends, Common Stock Document Annual Report Document Annual Report Entities [Table] Entities [Table] Senior Unsecured Notes Due August 2043 Senior Unsecured Notes Due August 2043 [Member] Senior Unsecured Notes Due August 2043 (Income) loss from equity investments (Notes 5 and 10) Income (Loss) from Equity Method Investments, Including Discontinued Operations Income (Loss) from Equity Method Investments, Including Discontinued Operations Regulatory Assets Regulatory Assets [Abstract] (Deprecated 2009-01-31) Income tax penalties expense Income Tax Examination, Penalties Expense Annual depreciation rate on straight-line basis Property, Plant and Equipment, Depreciation Rate Represents the annual rate at which long lived, physical assets used in the normal conduct of business and not intended for resale are depreciated. Canadian Natural Gas Pipelines Canadian Natural Gas Pipelines [Member] Canadian Natural Gas Pipelines [Member] Cash and Cash Equivalents Defined Benefit Plan, Cash and Cash Equivalents [Member] Canadian Mainline bridging amortization account Bridging Amortization Account [Member] Bridging Amortization Account [Member] Contributions from redeemable non-controlling interest Proceeds from Noncontrolling Interests Maximum exposure to loss Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Total options vested (in shares) Share Based Compensation Arrangement by Share Based Payment Award, Options, Vested in Period Represents the number of stock options vested during the period. Noncontrolling Interests Ownership Subsidiary, Ownership Percentage, Noncontrolling Owner Long-term debt repaid (Notes 19 and 20) Repayments of Long-Term Debt LEASES Lessor, Sales-type Leases [Text Block] Entity Interactive Data Current Entity Interactive Data Current Funds held on deposit Funds Held on Deposit [Member] Funds Held on Deposit [Member] Other Other jointly-owned entities Other Equity Method Investee [Member] Represents information pertaining to the other equity method investees. Junior subordinated debt, due 2079 Junior Subordinated Debt, Due 2079 [Member] Junior Subordinated Debt [Member] Maturing December 2028 Unsecured Credit Facility Maturing December 2028 [Member] Unsecured Credit Facility Maturing December 2026 [Member] Options Outstanding at December 31, 2025 Share-Based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term Senior Unsecured Notes Due September 2030 Senior Unsecured Term Loan Due September 2023 [Member] Senior Unsecured Term Loan Due September 2023 Funded Status – Plan Surplus Defined Benefit Plan, Funded (Unfunded) Status of Plan Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 3 [Member] Senior Unsecured Notes Due October 2024 3 Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Options, exercisable, intrinsic value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value OPEB surplus transferred to pay future active employee medical expenses Defined Benefit Plan, Plan Assets, Amount Transferred for Benefits Paid Defined Benefit Plan, Plan Assets, Amount Transferred for Benefits Paid Schedule of Additional Option Information Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block] Junior subordinated debt, due 2076 Junior Subordinated Debt, Due 2076 [Member] Junior Subordinated Debt, Due Two Thousand Seventy Six [Member] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Tax loss and credit carryforwards Deferred Tax Assets, Operating Loss Carryforwards Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Income tax differential related to regulated operations Effective Income Tax Rate Reconciliation, Related to Regulated Operations, Amount The portion of the difference between total income tax expense (benefit) as reported in the income statement for the year/accounting period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations that is attributable to regulated operations. Ownership [Domain] Ownership [Domain] COLUMBIA PIPELINES OPERATING COMPANY LLC Columbia Pipelines Operating Company LLC [Member] Columbia Pipelines Operating Company LLC Employee post-retirement benefits funding, net of expense (Note 26) Pension and Other Postretirement Benefits Expense (Reversal of Expense), Noncash Schedule of Future Lease Payments to be Received Under Operating Leases Lessor, Operating Lease, Payment to be Received, Maturity [Table Text Block] Plant operating costs and other Disposal Group, Including Discontinued Operation, Plant Operating Costs And Other Disposal Group, Including Discontinued Operation, Plant Operating Costs And Other Acquisitions and Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] 2027 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Operating and debt-service regulatory assets Operating and Debt Service Regulatory Assets [Member] Represents information pertaining to the operating and debt-service regulatory assets. Funded status adjustment Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income Funded Status Adjustment Pre-tax amount of the gain (loss) adjustment to other comprehensive income (loss) resulting from the funded status adjustment of the entity's defined benefit pension and other postretirement plans. Other Long-Term Assets (Note 14) Total other assets Other Long-Term Assets Other Assets, Noncurrent Accrued interest Accrued interest Interest Payable, Current Entity Central Index Key Entity Central Index Key Schedule of Repayments of Long-Term Debt Schedule of Maturities of Long-Term Debt [Table Text Block] Revenues Revenues (Power and Energy Solutions) Revenues Sales-type lease, net investment in lease, before allowance for credit loss Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss Carrying and fair values of non-derivative financial instruments Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Cost of removal Removal Costs [Member] Natural Gas Storage and Other Natural Gas Storage Equipment [Member] Represents information pertaining to the equipment used for the primary purpose of natural gas storage. Derivatives Defined Benefit Plan, Derivative [Member] Defined Benefit Plan [Table] Defined Benefit Plan [Table] Deferred Income Tax Assets Deferred Income Taxes and Other Assets [Abstract] Power purchase agreement, planned capacity (in megawatts) Power Purchase Agreement, Planned Capacity Power Purchase Agreement, Planned Capacity Odd numbered series of preferred shares Preferred Cumulative Shares including Series 1, Series 3, Series 5, Series 7, Series 9, Series 11, Series 13 and Series 15 [Member] Preferred Cumulative Shares including Series 1, Series 3, Series 5, Series 7, Series 9, Series 11, Series 13 and Series 15 [Member] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Contract liabilities (Note 16) Contract liabilities (Note 6) Contract with Customer, Liability, Current Loan from affiliate (Note 11) Proceeds From Affiliate Loan Loan From Affiliate Class of Stock [Domain] Class of Stock [Domain] Notional amount, energy (gwh) Notional amount, energy (mwh) Derivative, Nonmonetary Notional Amount, Energy Measure Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Canadian federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Subsequent Event Type [Axis] Subsequent Event Type [Axis] TC ENERGÍA MEXICANA, S. DE R.L. DE C.V. TC Energia Mexicana, S. DE R.L. DE C.V. [Member] TC Energia Mexicana, S. DE R.L. DE C.V. Equity Investments Deferred Tax Assets, Equity Method Investments Natural gas storage and other Natural Gas Storage And Other [Member] Natural Gas Storage And Other [Member] TransCanada Trust TransCanada Trust [Member] TransCanada Trust [Member] Sale consideration Disposal Group, Including Discontinued Operation, Consideration Long-Term Debt Long-Term Debt, Excluding Current Maturities Statement of Financial Position Location, Balance [Axis] Statement of Financial Position Location, Balance [Axis] Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract] Preferred Stock, Number of Shares, Par Value and Other Disclosure [Abstract] Canadian provincial taxes Effective Income Tax Rate Reconciliation at Canada Provincial Income Tax Rate, Percent Effective Income Tax Rate Reconciliation at Canada Provincial Income Tax Rate, Percent Compression Compression [Member] Represents the long lived, depreciable assets used for the primary purpose of compression of gas and liquids. Reclassification from accumulated other comprehensive Income (loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Deferred Income Tax Assets Deferred Tax Asset Deferred Tax Assets, Net [Abstract] Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Total AOCI Attributable to Parent [Member] Investments [Domain] Investments [Domain] Segmented Earnings (Losses) from Discontinued Operations Disposal Group, Including Discontinued Operation, Operating Income (Loss) Retirement Plan Funding Status [Axis] Defined Benefit Plan, Funding Status [Axis] Remaining Recovery/ Settlement Period (years) Regulatory Asset, Amortization Period Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Other components of net benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Other Components [Abstract] Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Other Components [Abstract] Restricted Interest and Financing Expense Deferred Tax Assets, Restricted Interest and Financing Expense Deferred Tax Assets, Restricted Interest and Financing Expense Ownership [Axis] Ownership [Axis] Loans and Leases Receivable Disclosure [Line Items] Loans and Leases Receivable Disclosure [Line Items] Amortization of past service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) PREFERRED SHARES Preferred Stock [Text Block] Schedule of Preferred Shares Schedule of Stock by Class [Table Text Block] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] LMCI Restricted Investments LMCI Restricted Investments [Member] LMCI Restricted Investments [Member] Millennium Millennium Gas Transmission System LP [Member] Millennium Gas Transmission System LP [Member] Equity Securities, U.S. Defined Benefit Plan, Equity Securities, US [Member] Operating losses Operating Loss Carryforwards Schedule of Long-Term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Even numbered series of preferred shares Even Numbered Series of Preferred Shares [Member] Even Numbered Series of Preferred Shares [Member] Spinoff of Liquids Pipelines business (Note 4) Impact of spinoff of Liquids Pipelines business Stockholders' Equity Note, Spinoff Transaction Total operating and other expenses Operating and other expenses Costs and Expenses Withholding tax Effective Income Tax Rate Reconciliation, Tax Settlement, Amount Counterparty Name [Domain] Counterparty Name [Domain] Schedule of Future Lease Payments Sales-Type and Direct Financing Leases, Payment to be Received, Maturity [Table Text Block] Restricted Investments Restricted Investments, Policy [Policy Text Block] Restricted Investments, Policy [Policy Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] One to two years Lessee, Operating Lease, Liability, to be Paid, Year Two Series 1 Series One Preferred Stock [Member] Represents information pertaining to the Series 1 cumulative preferred stock. Schedule of Accounts Payable and Other Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Term Loan August 2024 Term Loan August 2024 [Member] Term Loan August 2024 Investment Type [Axis] Investment Type [Axis] 2028 Defined Benefit Plan, Expected Future Benefit Payment, Year Three Notional amount, volume (bcf and mmbbls) Derivative, Nonmonetary Notional Amount, Volume, Net Derivative, Nonmonetary Notional Amount, Volume, Net Acquisitions, net of cash acquired Payments to Acquire Businesses, Gross Debentures Due March 2024 Debentures Due March 2024 [Member] Debentures Due March 2024 Options, outstanding, intrinsic value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Equity Securities, International Defined Benefit Plan, Equity Securities, International [Member] Defined Benefit Plan, Equity Securities, International [Member] Position [Domain] Position [Domain] Government of Canada, Five-Year Bond Yield Government of Canada, Five-Year Bond Yield [Member] Government of Canada, Five-Year Bond Yield [Member] Current yield (as a percent) Preferred Stock, Dividend Rate, Percentage Present value of unguaranteed residual value Sales-type Lease, Unguaranteed Residual Asset Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Shareholder Rights Plan Warrants and Rights Note Disclosure [Abstract] Schedule of Offsetting Assets Offsetting Assets [Table Text Block] Payment for receivables Expected credit loss provision Financing Receivable, Allowance for Credit Loss Change in fair value of derivative instruments recognized in OCI Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Less than one year Lessee, Operating Lease, Liability, to be Paid, Year One GOODWILL Goodwill Disclosure [Text Block] Non-Controlling Interests (Note 22) Non-Controlling Interests Equity, Attributable to Noncontrolling Interest Other Other Noncash Income (Expense) Reclassification of net investment hedge losses from AOCI to non-controlling interests related to sale percent Reclassification Of Net Investment Hedge Losses From AOCI To Non-Controlling Interests Related to Sale Percent Reclassification Of Net Investment Hedge Losses From AOCI To Non-Controlling Interests Related to Sale Percent Effect of cross-border taxes Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Percent Other revenues Other Income Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Employee post-retirement benefits Defined Benefit Plan Disclosure [Line Items] Canada Canadian CANADA Disposed of by sale Discontinued Operations, Disposed of by Sale [Member] Deferred Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Junior Subordinated Notes (Note 20) Junior subordinated notes (Note 20) Junior Subordinated Notes, Noncurrent Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Foreign exchange Foreign Exchange Contract [Member] Fair Value Estimate of Fair Value Measurement [Member] Revenue recognized Contract with Customer, Liability, Revenue Recognized Offsetting Assets [Table] Offsetting Assets [Table] Medium Term Notes Due October 2024 Medium Term Notes Due October 2024 3 [Member] Medium Term Notes Due October 2024 3 Retirement Plan Type [Domain] Retirement Plan Type [Domain] Other Other Miscellaneous Liabilities, Noncurrent Other Miscellaneous Liabilities, Noncurrent Rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Weighted average fair value (in Canadian dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Option, Nonvested, Weighted Average Exercise Price Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 5 [Member] Senior Unsecured Notes Due October 2024 5 OTHER LONG-TERM ASSETS Other Assets Disclosure [Text Block] Schedule of the Pre-Tax Amounts Recognized in OCI Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] (Increase) decrease in operating working capital (Note 28) (Increase) Decrease in Operating Working Capital Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital Other Natural Gas Pipelines Natural Gas Pipelines Other [Member] Represents information pertaining to other natural gas transmission systems including, but not limited to, the in service assets of Bison, Tamazunchale, Portland, North Baja, Guadalajara, Tuscarora and Ventures LP. Interest income and other Disposal Group, Including Discontinued Operation, Interest Income (Expense) Disposal Group, Including Discontinued Operation, Interest Income (Expense) Schedule of Junior Subordinated Notes Schedule of Junior Subordinated Debt [Table Text Block] Tabular disclosure of long-term junior subordinated debt obligations, including identification of lender type, repayment terms, features, collateral requirements and other information. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer. Accumulated other comprehensive income (loss) (Note 25) Accumulated Other Comprehensive Income (Loss), Net of Tax Junior subordinated notes issued, net of issue costs Proceeds from Issuance of Subordinated Long-Term Debt Commitments under operating leases Long-Term Purchase Commitment [Line Items] Mexico foreign exchange exposure Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent Retirement Plan Sponsor Location [Domain] Retirement Plan Sponsor Location [Domain] 2026 Long-Term Debt, Maturity, Year One Financial Instruments [Domain] Financial Instruments [Domain] Other comprehensive income (loss) on equity investments OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Receivables from contracts with customers Receivables, Long-Term Contracts or Programs Deferred tax liabilities, gross Deferred Tax Liabilities, Gross Schedule of Components of OCI related to Derivatives in Cash Flow Hedging Relationships Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block] 2030 Long-Term Debt, Maturity, Year Five Maturing December 2030 Unsecured Credit Facility Maturing December 2030 [Member] Unsecured Credit Facility Maturing December 2030 Reclassification to net income of (gains) losses on cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Senior Unsecured Notes One Due March 2026 Senior Unsecured Notes One Due March 2026 [Member] Senior Unsecured Notes One Due March 2026 Inventories Inventory, Net Three to four years Sales-Type and Direct Financing Leases, Payment to be Received, Year Four Minimum Minimum [Member] Foreign federal and state operating losses Operating Loss Carryforwards, Foreign, Federal And State, Valuation allowance Operating Loss Carryforwards, Foreign, Federal And State, Valuation allowance Amount accrued related to operating facilities for the estimated expenses to remediate the sites Accrual for Environmental Loss Contingencies Fair Value Measurement [Domain] Fair Value Measurement [Domain] RATE-REGULATED BUSINESSES Rate Regulated Businesses Disclosure [Text Block] The disclosure of Canada and United States regulated operations including a summary of regulatory assets and liabilities. Senior Unsecured Notes Due November 2025 Senior Unsecured Notes Due November 2025 [Member] Senior Unsecured Notes Due November 2025 Deferred Income Tax Liabilities Deferred Tax Liabilities, Net [Abstract] Cash paid for amounts included in the measurement of operating lease liabilities Operating Lease, Payments Mexico Mexico and International [Member] Mexico and International [Member] Other Comprehensive Income (Loss) Other Comprehensive Income (Loss), before Tax Discontinued Operations Discontinued Operations [Member] Dividends payable Dividends Payable Transition services agreement, term Transition Services Agreement Term Transition Services Agreement Term Foreign Current Foreign Tax Expense (Benefit) Goodwill Goodwill [Roll Forward] Assets and (liabilities), net Derivative Assets (Liabilities), at Fair Value, Net Revenues Disposal Group, Including Discontinued Operation, Revenue COLUMBIA PIPELINES HOLDING COMPANY LLC Columbia Pipelines Holding Company LLC [Member] Columbia Pipelines Holding Company LLC Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Columbia Pipelines Group Columbia Pipelines Group [Member] Columbia Pipelines Group Weighted average interest rate per annum Short-Term Debt, Weighted Average Interest Rate, at Point in Time Total fair value of options that have vested Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested in Period, Fair Value Schedule of Interest Expense Schedule Of Interest Expense [Table Text Block] Tabular disclosure of the components of interest expense charged or capitalized during the period including amortization and other financial charges. Derivative [Table] Derivative [Table] Energir L.P Energir L.P [Member] Energir L.P Credit Risk Related Contingent Features Derivative, Credit Risk Related Contingent Features [Abstract] Business acquisition, percentage of voting interests acquired Business Combination, Voting Equity Interest Acquired, Percentage Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Number of shares outstanding (in shares) Preferred Stock, Shares Outstanding Cost to maintain Line of Credit Facility, Commitment Fee Amount NOVA GAS TRANSMISSION LTD. NOVA GAS TRANSMISSION LTD. Nova Gas Transmission LTD [Member] Represents information pertaining to NOVA Gas Transmission Ltd. LONG-TERM DEBT Long-Term Debt [Text Block] Maturing within 1-5 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Other Commitments Other Commitments [Abstract] Other comprehensive income (loss), before reclassifications Other Comprehensive Income (Loss), before Reclassifications, before Tax CHANGES IN OPERATING WORKING CAPITAL CHANGES IN OPERATING WORKING CAPITAL 180d04c6-53cd-11e3-b035-22000a1e8102 Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Power and Energy Solutions Power and Energy Solutions [Member] Represents information pertaining to the Power and energy segment of the entity which primarily consists of the Company's investment in electrical power generation plants and non-regulated natural gas storage facilities. Junior Subordinated Notes [Abstract] Junior Subordinated Notes [Abstract] INCOME TAXES Income Tax Disclosure [Text Block] Transmission Systems [Domain] Transmission Systems [Domain] Categorization of transmission systems. Common Class A Common Class A [Member] Total trading activity Total Trading Activity [Member] Total Trading Activity [Member] Goodwill, net Goodwill, Net Of Impairment Goodwill, Net Of Impairment Aggregate fair value of derivative instruments in a net liability position Derivative, Net Liability Position, Aggregate Fair Value Derivative Instrument Liabilities Derivative Liability, Subject to Master Netting Arrangement, before Offset of Collateral [Abstract] Net Amounts Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Mexico Natural Gas Pipelines Mexico Natural Gas Pipelines [Member] Mexico Natural Gas Pipelines [Member] Medium Term Notes One Due March 2026 Medium Term Notes One Due March 2026 [Member] Medium Term Notes One Due March 2026 Total Equity Balance at beginning of year Balance at end of year Stockholders' equity Equity, Including Portion Attributable to Noncontrolling Interest Document Type Document Type Significant Unobservable Inputs (Level III) Fair Value, Inputs, Level 3 [Member] Product and Service [Axis] Product and Service [Axis] Senior Unsecured Notes Due January 2034 Senior Unsecured Notes Due January 2034 [Member] Senior Unsecured Notes Due January 2034 Fixed Income Securities, Canadian Bonds, Federal Defined Benefit Plan, Canadian Federal Debt Securities [Member] Defined Benefit Plan, Canadian Federal Debt Securities [Member] Debt Instrument Interest Rate Period [Domain] Debt Instrument Interest Rate Period [Domain] [Domain] for Debt Instrument Interest Rate Period [Axis] Revenues from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Series 2, Series 4, Series 6 and Series 10 Preferred Stock Series Two, Four, Six and Ten Preferred Stock [Member] Series Two, Four, and Six Preferred Stock [Member] Non-taxable capital (gain) loss Effective Income Tax Rate Reconciliation, Non-Taxable Portion Of Capital Gains, Percent Effective Income Tax Rate Reconciliation, Non-Taxable Portion Of Capital Gains, Percent Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 8 [Member] Senior Unsecured Notes Due October 2024 8 Total current assets Current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Gains (losses) on settlement of financial instruments Payments for (Proceeds from) Hedge, Financing Activities Options forfeited/expired (in Canadian dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Regulatory Asset [Domain] Regulatory Asset [Domain] TRANSCANADA PIPELINES LIMITED TCPL TransCanada PipeLines Limited [Member] Represents information pertaining to TransCanada PipeLines Limited. Depreciation and amortization Disposal Group, Including Discontinued Operation, Depreciation and Amortization Disposal Group Name [Axis] Disposal Group Name [Axis] Total intrinsic value of options exercised Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value Distributions received from equity investments Equity Method Investment Distributed Earnings Represents amount of dividends and distributions from equity accounted investments including distributions that constitute a return of investment. Schedule of Other Long-Term Assets Schedule of Other Assets [Table Text Block] Net income (loss) attributable to common shares from continuing operations Net Income (Loss) Available to Common Stockholders, Basic Loans to affiliate (issued) repaid, net Origin of Notes Receivable from Related Parties, Repaid (Issued) Origin of Notes Receivable from Related Parties, Repaid (Issued) Regulatory assets (Note 12) Less: Current portion included in Other current assets (Note 7) Regulatory Asset, Current Entity Information [Line Items] Entity Information [Line Items] Columbia Gulf Columbia Gulf Transmission [Member] Columbia Gulf Transmission [Member] Current Liabilities Liabilities, Current [Abstract] Weighted Average Remaining Contractual Life Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Realized gains (losses) in the year Realized Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net Realized Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net Annual Information Form Annual Information Form Quoted Prices in Active Markets (Level I) Fair Value, Inputs, Level 1 [Member] Entity Primary SIC Number Entity Primary SIC Number Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 7 [Member] Senior Unsecured Notes Due October 2024 7 Other Assets [Abstract] Other Assets [Abstract] Unrealized Foreign Exchange on Long-Term Debt Unrealized Foreign Exchange on Long-Term Debt, Carryforwards Unrealized Foreign Exchange on Long-Term Debt, Carryforwards Redemption price per share (in Canadian dollars per share) Preferred Stock, Redemption Price Per Share Senior Unsecured Term Loan Various 2024 Senior Unsecured Term Loan Various 2024 [Member] Senior Unsecured Term Loan Various 2024 Diluted (in dollars per share) Earnings Per Share, Diluted Four to five years Lessor, Operating Lease, Payment to be Received, Year Five Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Maturing within 5-10 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Mexico foreign exchange exposure Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount Senior Unsecured Term Loan Senior Unsecured Term Loan [Member] Senior Unsecured Term Loan Dividend reinvestment and share purchase plan Stock Issued During Period, Value, Dividend Reinvestment Plan Consolidation Items [Domain] Consolidation Items [Domain] Net Income (Loss) from Discontinued Operations, Net of Tax (Note 4) Net Income (Loss) from Discontinued Operations, Net of Tax Net Income (Loss) from Discontinued Operations, Net of Tax Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Impairment of Equity Method Investments Impairment of Equity Method Investments, Policy [Policy Text Block] Impairment of Equity Method Investments, Policy Auditor Location Auditor Location Unsecured Term Loan Due November 2023 Unsecured Term Loan Due November 2023 [Member] Unsecured Term Loan Due November 2023 VIE, not primary beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] EQUITY INVESTMENTS Equity Method Investments and Joint Ventures Disclosure [Text Block] Current portion included in Other current assets (Note 7) Sales-Type Lease, Net Investment in Lease, after Allowance for Credit Loss, Current Canada - provincial Current Provincial Tax Expense (Benefit) Current Provincial Tax Expense (Benefit) Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Actuarial (gain) loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Domestic Tax Jurisdiction Domestic Tax Jurisdiction [Member] Employee contributions Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant Regulatory Liability [Domain] Regulatory Liability [Domain] Noncontrolling Interest [Abstract] Noncontrolling Interest [Abstract] Net investment in leases (Note 9) Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss, Current Net gains (losses) included in Net income (loss) Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Commodities Commodity [Member] Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Columbia Gas Columbia Gas Transmission [Member] Columbia Gas Transmission [Member] Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Income tax payments (refunds) Income Taxes Paid, Net Depreciation and amortization Depreciation and amortization Depreciation, Depletion and Amortization, Excluding Discontinued Operations Depreciation, Depletion and Amortization, Excluding Discontinued Operations Contributions to equity investments Payments to Acquire Equity Method Investments, Capital Spending Payments to Acquire Equity Method Investments, Capital Spending Canada – export Canada Export [Member] Represents information pertaining to the export revenues of the entity by geographic region. Current assets of discontinued operations (Note 4) Current assets of discontinued operations Current assets of discontinued operations (Note 4) Disposal Group, Including Discontinued Operation, Assets, Current Columbia Gas and Columbia Gulf Columbia Gas and Columbia Gulf [Member] Columbia Gas and Columbia Gulf Outstanding Outstanding Outstanding Long-Term Debt, Gross Off-balance sheet Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure, Off Balance Sheet [Abstract] Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure, Off Balance Sheet Series 6 Series Six Preferred Stock [Member] Represents information pertaining to the Series 6 cumulative preferred stock. PLANT, PROPERTY AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Total operating lease payments Lessee, Operating Lease, Liability, to be Paid Market Market [Member] Market Distributions declared to non-controlling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Total pre-tax amounts recognized in OCI Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Series 2 Series Two Preferred Stock [Member] Represents information pertaining to the Series 2 cumulative preferred stock. Junior subordinated debt, due 2065 Junior Subordinated Debt, Due 2065 [Member] Junior Subordinated Debt, Due 2065 Intersegment eliminations Intersegment Eliminations [Member] Schedule of the Pre-Tax Amounts Recognized in AOCI Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block] Variable interest entity ownership percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Schedule of Foreign Exchange Contracts Schedule of Foreign Exchange Contracts, Statement of Financial Position [Table Text Block] Deemed common equity, percent Deemed Common Equity Percentage Represents the percentage of deemed common equity required for approving ROE by the National Energy Board (NEB). Income from non-controlling interests Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent EQUITY Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Fixed income securities Fixed Income Securities [Member] Tuscarora TUSCARORA GAS TRANSMISSION COMPANY Tuscarora Gas Transmission Company [Member] Represents information pertaining to Tuscarora Gas Transmission Company, a natural gas transmission system extending from Malin, Oregon, to Wadsworth, Nevada. Sales-type lease income Sales-type lease income Sales-type Lease, Lease Income Schedule of Equity Investments Equity Method Investments [Table Text Block] Plant, Property and Equipment (Note 8) Plant, Property and Equipment Net Book Value Property, Plant and Equipment, Net Series 3 Series Three Preferred Stock [Member] Represents information pertaining to the Series 3 cumulative preferred stock. Property, plant and equipment excluding under construction Property, Plant and Equipment, Excluding Asset Under Construction [Member] Represents information pertaining to property, plant and equipment excluding asset under construction. (Increase) decrease in Accounts receivable Increase (Decrease) in Accounts Receivable Inventories Inventory, Policy [Policy Text Block] Deferred tax assets, net of Valuation allowance Deferred Tax Asset, Valuation Allowance. Net Deferred Tax Asset, Valuation Allowance. Net Entity Current Reporting Status Entity Current Reporting Status Receivables [Abstract] Derivative [Line Items] Derivative [Line Items] Repayments of Long-term Debt [Abstract] Repayments of Long-Term Debt [Abstract] Canadian Mainline long-term adjustment account Long-Term Adjustment Account [Member] Long-Term Adjustment Account [Member] Consolidated Entities [Domain] Consolidated Entities [Domain] Fair value of plan assets Defined Benefit Plan, Plan Assets Including Future Transferrable Amount Defined Benefit Plan, Plan Assets Including Future Transferrable Amount Expected income tax expense Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Change in fair value of net investment hedges Accumulated Net Gain (Loss) from Investment Hedges Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Net Gain (Loss) from Investment Hedges Including Portion Attributable to Noncontrolling Interest [Member] Corporate Corporate Segment [Member] Foreign currency translation gains and losses on net investment in foreign operations Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Series 11 Series 11 Cumulative Preferred Stock [Member] Series 11 Cumulative Preferred Stock [Member] Financial Instrument [Axis] Financial Instrument [Axis] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Increase (decrease) in Accounts payable and other Increase (Decrease) in Accounts Payable and Other Operating Liabilities Asset retirement obligations Asset Retirement Obligations, Noncurrent Amount Repayments of Debt State and local income taxes, net of federal effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Other Other Investment [Member] Other Investment Contributions to equity investments, net of distributions Payments To Acquire Equity Method Investments, Noncontrolling Interest Distribution, Before Tax Payments To Acquire Equity Method Investments, Noncontrolling Interest Distribution, Before Tax Net change in the Level III fair value category Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Net proceeds Proceeds from Issuance of Long-Term Debt Current Fiscal Year End Date Current Fiscal Year End Date Assumed average annual rate of increase in the per capita cost of covered health care benefits Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Number of rights entitled to each common share (in shares) Class of Warrant or Right, Number of Securities Called by Each Warrant or Right Amount Stockholders Equity [Roll Forward] Stockholders Equity Expected life (years) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Debt converted Debt Conversion, Converted Instrument, Amount Number of shares available for grant (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Schedule of Guarantees Schedule of Guarantor Obligations [Table Text Block] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Long-term debt Long-Term Debt, Amount Recorded At Fair Value Long-Term Debt, Amount Recorded At Fair Value Foreign Exchange Interest rate Interest rate contracts Interest Rate Contract [Member] Gross Derivative Instruments Derivative Asset, Not Subject to Master Netting Arrangement Operating and other expenses Disposal Group, Including Discontinued Operation, Operating Expense NON-CONTROLLING INTERESTS Noncontrolling Interest Disclosure [Text Block] Asset impairment charge and other (Note 4) Asset Impairment Charge And Other Asset Impairment Charge And Other Distributions received from operating activities of equity investments (Note 10) Proceeds from Equity Method Investment, Distribution Schedule of Fair Value of Assets and Liabilities Measured on a Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Unrecognized tax benefit at beginning of year Unrecognized Tax Benefit at End of Year Unrecognized Tax Benefits Weighted Average Number of Common Shares (millions) (Note 23) Weighted Average Number of Shares Outstanding, Diluted [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] 2027 Long-Term Debt, Maturity, Year Two Asset impairment charge and other Disposal Group, Including Discontinued Operation, Asset Impairment Charge And Other Disposal Group, Including Discontinued Operation, Asset Impairment Charge And Other LEASES Lessee, Operating Leases [Text Block] Net cash (used in) provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Equity interest percentage Noncontrolling Interest, Increase from Sale of Parent Equity Interest Percentage Noncontrolling Interest, Increase from Sale of Parent Equity Interest Percentage Document Registration Statement Document Registration Statement Deferred income tax liabilities on the unremitted earnings of foreign investments Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability, Undistributed Earnings of Foreign Subsidiaries Fair Value Total Derivatives Derivative, Fair Value, Net Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Lease receivable Sales-type Lease, Lease Receivable Commodity purchases resold Cost of Product and Service Sold Amortization of actuarial gains (losses) Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Senior Unsecured Term Loan Due May 2026 Senior Unsecured Term Loan Due May 2026 [Member] Senior Unsecured Term Loan Due May 2026 Disposal Group Classification [Domain] Disposal Group Classification [Domain] Impairment charges after tax Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Portion Attributable to Parent Revenues, including intersegment revenues Revenues, Including Intersegment Sales Revenues, Including Intersegment Sales Schedule of Reclassifications out of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Capital Spending Banking Regulation, Total Capital [Abstract] Interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] Entity Tax Identification Number Entity Tax Identification Number Amortization of regulatory asset Defined Benefit Plan, Amortization of Regulatory Assets The amount of amortization of regulatory assets recognized in net periodic benefit cost. Medium-Term Notes, Maturity between 2026 and 2030 Medium-Term Notes, Maturity between 2026 and 2030 [Member] Medium-Term Notes, Maturity between 2025 and 2030 [Member] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Pipeline abandonment trust balances Abandonment Costs [Member] Abandonment Costs [Member] Business contact Business Contact [Member] Outstanding at the beginning of the period (in Canadian dollars per share) Outstanding at the end of the period (in Canadian dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Deferred Tax Asset Carryforward, Deferred Tax Asset [Member] Carryforward, Deferred Tax Asset Trade payables Accounts Payable, Trade, Current Cash Flow Hedges Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member] Sales Short [Member] Schedule of Weighted Average Shares Schedule of Weighted Average Number of Shares [Table Text Block] Other Long-Term Liabilities Liabilities, Other than Long-Term Debt, Noncurrent Common shares issued (in shares) Common Stock, Shares, Issued Restricted Investments Restricted Investments, Noncurrent 2029 Long-Term Debt, Maturity, Year Four Regulatory Liabilities Regulatory Liability Weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Equity Securities, Global Defined Benefit Plan, Equity Securities, Global [Member] Defined Benefit Plan, Equity Securities, Global [Member] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Interest expense (Note 19) Interest expense Interest expense (Note 19) Interest Expense, Nonoperating Series 9 Series Nine Preferred Stock [Member] Series 9 Preferred Stock [Member] Fair value of derivative instruments (Note 27) Derivative Asset, Current Guarantees Guarantees, Indemnifications and Warranties Policies [Policy Text Block] Corporate Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Security Exchange Name Security Exchange Name Foreign Income Tax Paid, Foreign, after Refund Received Benefit obligation and fair value of plan assets for plans that are not fully funded Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract] Non-current liabilities Liabilities, Noncurrent Capital expenditures Capital Addition Purchase Commitments [Member] One to two years Lessor, Operating Lease, Payment to be Received, Year Two Cash received from factoring arrangement (Note 9) Proceeds from Factoring Agreement Proceeds from Factoring Agreement Total Derivatives Derivative Instrument Assets Derivative Asset, Subject to Master Netting Arrangement, before Offset of Collateral [Abstract] Power Energy Related Derivative [Member] Price of shares issued from treasury Stock Issued During Period, Dividend Reinvestment Plan, Shares Issued From Treasury, Price, Percent Stock Issued During Period, Dividend Reinvestment Plan, Shares Issued From Treasury, Price, Percent GAS TRANSMISSION NORTHWEST LLC Gas Transmission Northwest Corporation [Member] Represents information pertaining to Gas Transmission Northwest Corporation. Revolving credit facility, borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Preferred share dividends Dividends, Preferred Stock Dividend reinvestment and share purchase plan (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Factoring arrangement (Note 9) Supplier Finance Program, Obligation, Current Transmission Systems [Axis] Transmission Systems [Axis] Information pertaining to transmission systems. Infrastructure Infrastructure Investments [Member] Infrastructure Investments [Member] Prepaid expenses Prepaid Expense, Current Contact Personnel Name Contact Personnel Name Employee contributions Defined Benefit Plan, Plan Assets, Contributions by Plan Participant FOREIGN EXCHANGE (GAINS) LOSSES, NET Foreign Currency Disclosure [Text Block] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Employee post-retirement benefits (Note 26) Other long-term liabilities (Note 17) Liability, Defined Benefit Plan, Noncurrent Foreign Currency [Abstract] Statement [Line Items] Statement [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Cash and cash equivalents Cash and Cash Equivalent Equity Securities, Emerging Defined Benefit Plan, Equity Securities, Emerging [Member] Defined Benefit Plan, Equity Securities, Emerging [Member] Common Shares (Note 23) Common shares Common Stock [Member] Notes payable (Note 15) Outstanding Other Short-Term Borrowings Senior Unsecured Notes Due August 2063 Senior Unsecured Notes Due August 2063 [Member] Senior Unsecured Notes Due August 2063 Increase (Decrease) in Cash and Cash Equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Notes payable Notes Payable, Current Mexico MEXICO Unrealized (gains) losses on financial instruments (Note 27) Unrealized Gain (Loss) on Investments Guarantees Guarantor Obligations [Line Items] ACCOUNTING POLICIES Significant Accounting Policies [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Other current assets Other Current Assets [Member] More than five years Lessee, Operating Lease, Liability, to be Paid, after Year Five Security Reporting Obligation Security Reporting Obligation Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Deferred income taxes Deferred Income Taxes [Member] Deferred Income Taxes [Member] Senior Unsecured Revolving Credit Facility Various 2023 Senior Unsecured Revolving Credit Facility Various 2023 [Member] Senior Unsecured Revolving Credit Facility Various 2023 Fixed Income Securities, U.S. Bonds, Corporate Debt Security, Corporate, US [Member] Foreign Plan Foreign Plan [Member] Long-term debt (excluding junior subordinated notes) Long Term Debt Excluding Junior Subordinated Notes [Member] Debt arrangement having an initial term longer than one year or beyond the normal operating cycle, if longer. Excludes junior subordinated notes. Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Other long-term assets Other Noncurrent Assets [Member] Interest rate swap agreements Interest Rate Swap [Member] Long-Term Debt Transaction Costs and Issuance Costs Debt, Policy [Policy Text Block] Cash transferred to South Bow, net of debt settlements Payments of Financing Costs Impairment of Long-Lived Assets and Impairment of Financial Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Income (Loss) from Equity Investments (Note 10) Income (loss) from equity investments Income (Loss) from Equity Investments Income (Loss) from Equity Method Investments Leases [Abstract] Leases [Abstract] Gross increase - tax positions in prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Schedule of Other Long-Term Liabilities Other Noncurrent Liabilities [Table Text Block] Senior Unsecured Term Loan Various 2025 Senior Unsecured Term Loan Various 2025 [Member] Senior Unsecured Term Loan Various 2025 Three to four years Lessor, Operating Lease, Payment to be Received, Year Four Operating Activities [Axis] Operating Activities [Axis] Contract assets (Note 7) Contract assets (Note 6) Contract with Customer, Asset, after Allowance for Credit Loss, Current Schedule of Discontinued Operations Disposal Groups, Including Discontinued Operations [Table Text Block] Total financial charges Interest Income (Expense), Nonoperating Senior Unsecured Notes Due November 2032 Senior Unsecured Notes Due November 2032 [Member] Senior Unsecured Notes Due November 2032 Basic (in dollars per share) Earnings Per Share, Basic Schedule of Credit Facilities Schedule of Line of Credit Facilities [Table Text Block] Notes payable Short-term debt Commercial Paper [Member] Reclassification of net investment hedge losses related to the spinoff Reclassification Of Net Investment Hedge Losses Related To Spinoff Reclassification Of Net Investment Hedge Losses Related To Spinoff Entity Addresses, Address Type [Axis] Entity Addresses, Address Type [Axis] Unrealized actuarial gains and losses and reclassification of actuarial gains and losses of pension and other post-retirement benefits Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member] Financial charges Disposal Group, Including Discontinued Operation, Non Operating Expense (Income) Disposal Group, Including Discontinued Operation, Non Operating Expense (Income) Deferred tax assets, gross Deferred Tax Assets, Gross Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Other comprehensive income (loss) (Note 25) Other comprehensive income (loss) attributable to controlling interests Other Comprehensive Income (Loss), Net of Tax Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Future revenues, remaining performance obligation Revenue, Remaining Performance Obligation, Amount Emissions expense payable Emissions Expense Payable, Current Emissions Expense Payable, Current Moving average period of basis used to determine expected return on plan assets Defined Benefit Plan Moving Average Period of Basis used to Determine Expected Return on Plan Assets Represents the moving average period used to determine expected return on plan assets under the defined benefit plan. OTHER LONG-TERM LIABILITIES Deferred Liabilities Non-current Disclosure [Text Block] The entire disclosure for noncurrent deferred liabilities. South Bow - transition of plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan Category of Item Purchased [Axis] Category of Item Purchased [Axis] VIE, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Financial Charges Interest Income (Expense), Operating [Abstract] Contributions to equity investments Payments to Acquire Equity Method Investments Components of OCI related to derivatives Derivative Instruments, Gain (Loss) [Line Items] Expense for stock options Share-Based Payment Arrangement, Expense Hedging Designation [Domain] Hedging Designation [Domain] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current Assets Assets, Current [Abstract] Total Liabilities and Equity Liabilities and Equity Foreign Currency Transactions and Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] South Bow - transition of benefit obligation Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change Pension and Other Post-Retirement Benefit Plan Adjustments Pension and other post-retirement benefit plan adjustments Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Equity investments Deferred Tax Liabilities, Investment in Noncontrolled Affiliates Number of
Options Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] U.S. Natural Gas Pipelines U.S. Natural Gas Pipelines [Member] U.S. Natural Gas Pipelines [Member] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] LNG Canada LNG Canada [Member] LNG Canada Real estate Employee Benefit Plan, Real Estate [Member] Term Loan Due August 2024 Term Loan Due August 2024 [Member] Term Loan Due August 2024 Other Deferred Tax Assets, Other Equity Method Investment [Table] Equity Method Investment [Table] Guarantees [Abstract] Guarantees [Abstract] Letters of credit received by the Company Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Security Not Offset Interest expense and Foreign exchange gains (losses), net Interest Expense And Foreign Exchange Gains (Losses), Net Interest Expense And Foreign Exchange Gains (Losses), Net Accounting Policies [Abstract] Accounting Policies [Abstract] Amount of unrealized (losses) / gains in the year Unrealized Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net Unrealized Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net Revolving and demand credit facility Revolving and Demand Credit Facility [Member] Represents information pertaining to the revolving and demand credit facilities. Schedule of Maturities of Operating Lease Liabilities Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] GTN GTN [Member] Represents information pertaining to GTN, a natural gas transmission system extending from the B.C./Idaho border to the Oregon/California border. Other components of net benefit cost Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component Net Income (Loss) from Continuing Operations Net Income (Loss) from Continuing Operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Operating lease liabilities Operating Lease, Liability Total payments to be received Lessor, Operating Lease, Payment to be Received LIABILITIES Liabilities [Abstract] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Non-controlling interests on acquisition of Texas Wind Farms (Note 29) Noncontrolling Interest, Increase from Business Combination Operating costs Costs And Expenses, Including Intersegment Costs And Expenses, Including Intersegment Stock redeemed during period (in shares) Stock Redeemed or Called During Period, Shares Other Long-Term Liabilities (Note 17) Other long-term liabilities Other Liabilities, Noncurrent Deferred income taxes - U.S. Tax Reform Deferred Income Taxes - US Tax Reform [Member] Deferred Income Taxes - US Tax Reform [Member] Trading Activity, by Type [Domain] Trading Activity, by Type [Domain] Goodwill, gross Goodwill, Before Impairment Goodwill, Before Impairment Difference between the carrying value of the investment and the underlying equity in the net assets Equity Method Investment, Difference Between Carrying Amount and Underlying Equity Unrealized gain (loss) on hedged item Hedged items Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Variable Interest Entity [Table] Variable Interest Entity [Table] Senior Unsecured Notes Due November 2053 Senior Unsecured Notes Due November 2053 [Member] Senior Unsecured Notes Due November 2053 Canada - provincial Deferred Provincial Income Tax Expense (Benefit) Deferred Provincial Income Tax Expense (Benefit) Regulatory Liabilities Regulatory Liabilities [Abstract] (Deprecated 2009-01-31) Current portion of long-term debt (Note 19) Current portion of long-term debt Current portion of long-term debt Long-Term Debt, Current Maturities Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Two to three years Lessee, Operating Lease, Liability, to be Paid, Year Three Canadian junior subordinated debt, due 2077 Junior Subordinated Debt, Due 2077 2 [Member] Junior Subordinated Debt, Due 2077 [Member] Comprehensive Income (Loss) Attributable to Controlling Interests Comprehensive Income (Loss), Net of Tax, Attributable to Parent Disposal Group Name [Domain] Disposal Group Name [Domain] Total amount outstanding under letters of credit Defined Benefit Plan, Letters of Credit, Amount The total amount of the contingent obligation under letters of credit provided to the defined benefit plan by the entity outstanding as of the reporting date. Schedule of Geographic Components of Income Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Maturing within 1 year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Income from equity investments Effective Income Tax Rate Reconciliation, Equity Investments, Percent Effective Income Tax Rate Reconciliation, Equity Investments, Percent Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 6 [Member] Senior Unsecured Notes Due October 2024 6 Schedule of Net Change in the Level III Fair Value Category Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Total cash contributions Post-retirement and Post-employment Plans, Defined Benefit and Defined Contribution and Other Benefit Plans Cash Payments Represents the aggregate cash payments made by the reporting entity for the defined benefit plans, defined contribution plans, and other benefit plans related to post-retirement and post-employment plans. Class of Stock [Line Items] Class of Stock [Line Items] Deferred Income Tax Liabilities (Note 18) Deferred Income Tax Liabilities Deferred Income Tax Liabilities, Net Expected long-term rate of return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets Postretirement benefit costs Postretirement Benefit Costs [Member] Accumulated depreciation for facilities accounted for as operating leases Property, Plant, and Equipment, Lessor Asset under Operating Lease, Accumulated Depreciation Schedule of Unrealized Gain (Loss) on Investments Unrealized Gain (Loss) on Investments [Table Text Block] Long-term debt Long-term Debt Long-Term Debt Current Liabilities Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract] Schedule of Components of Other Comprehensive Income (Loss) Comprehensive Income (Loss) [Table Text Block] Legal Entity [Axis] Legal Entity [Axis] Non-regulated natural gas storage facilities (in billion cubic feet) Public Utilities, Property, Plant and Equipment, Non-Regulated Natural Gas Storage Facilities, in Billion Cubic Feet Public Utilities, Property, Plant and Equipment, Non-Regulated Natural Gas Storage Facilities, in Billion Cubic Feet Total assets Assets Assets Investing Activities Cash Provided by (Used in) Investing Activity, Continuing Operation [Abstract] Deferred income taxes Deferred Income Tax Charge [Member] Company debt or common shares included in plan assets, amount Defined Benefit Plan, Plan Assets, Employer, Related Party, Amount Regulatory Liability [Axis] Regulatory Liability [Axis] Geographical [Domain] Geographical [Domain] Fixed Income Securities, International, Net forward contract Net Forward Contract, International [Member] Net Forward Contract, International Schedule of Distribution Received and Contribution made to Equity Investments Schedule Of Distribution Received And Contribution Made To Equity Investments [Table Text Block] Schedule Of Distribution Received And Contribution Made To Equity Investments Income Taxes Income Tax, Policy [Policy Text Block] Off-balance Sheet potential exposure to guarantees Variable Interest Entity, Nonconsolidated, Carrying Amount, Off-balance Sheet, Potential Exposure to Guarantees Variable Interest Entity, Nonconsolidated, Carrying Amount, Off-balance Sheet, Potential Exposure to Guarantees Other segment items Segment Reporting, Other Segment Item, Amount Private equity funds Private Equity Funds [Member] Series 7 Series Seven Preferred Stock [Member] Series 7 Preferred Stock [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Capital loss Capital Loss Carryforward Capital Loss Carryforward Variable Interest Entities Consolidation, Variable Interest Entity, Policy [Policy Text Block] Dividends Declared per Common Share (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Long-term debt Long-Term Debt, Excluding Current Portion [Member] Long-Term Debt, Excluding Current Portion [Member] ROU assets obtained in exchange for new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Reduction to additional paid-in capital Noncontrolling Interest, Loss On Sale, Reduction To Additional Paid In Capital Noncontrolling Interest, Loss On Sale, Reduction To Additional Paid In Capital Operating lease cost Lease, Cost [Abstract] Significant Other Observable Inputs (Level II) Level II Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] State and local income taxes, net of federal effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount NOTES PAYABLE Short-Term Debt [Text Block] Operating and debt-service regulatory liabilities Operating and Debt Service Regulatory Liabilities [Member] Represents information pertaining to the operating and debt-service regulatory liabilities. Equity Investments (Note 10) Equity Investments Equity Investments (Note 10) Equity Method Investments Business Combination [Domain] Business Combination [Domain] Net Gain (Loss) on Sale of Assets (Note 29) Net (gain) loss on sale of assets (Note 29) Net gain (loss) on sale of assets Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Related party Related Party [Member] Change in Plan Assets Net change in the Level III fair value category Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Period two Period Two [Member] Period Two [Member] Schedule of Provision for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Aggregate Net Investment in Leases Sales-type Lease, Lease Income [Table Text Block] Plant, Property and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Four to five years Sales-Type and Direct Financing Leases, Payment to be Received, Year Five Capital loss Capital Loss Carryforward, Valuation Allowance Capital Loss Carryforward, Valuation Allowance Junior subordinated notes Junior Subordinated Debt [Member] United States United States UNITED STATES Net realized gains related to the interest component Derivative Net Realized Gain (Loss) Related to Interest Component Represents the amount of net realized gains (losses) related to the interest component of derivative instrument. Fair value adjustments Debt, Fair Value Adjustments During Period Debt, Fair Value Adjustments During Period Changes in valuation allowances Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Current Assets Disposal Group, Including Discontinued Operation, Assets, Current [Abstract] Volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Retained Earnings (Accumulated Deficit) Retained Earnings [Member] Transportadora de Gas Natural de la Huasteca Transportadora de Gas Natural de la Huasteca [Member] Transportadora de Gas Natural de la Huasteca Transfers to Level II Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 2 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 2 Series 10 Series 10 Cumulative Redeemable Preferred Stock [Member] Series 10 Cumulative Redeemable Preferred Stock [Member] Income Tax Jurisdiction [Axis] Income Tax Jurisdiction [Axis] Columbia Columbia Pipeline Group Inc [Member] Columbia Pipeline Group Inc [Member] Cash and Cash Equivalents, Beginning of year Cash and Cash Equivalents, End of year Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Income Statement [Abstract] Schedule of the Net Change in the Level III Fair Value Category Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block] Funded status based on accumulated benefit obligation Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] Property, plant and equipment, including under construction Property, Plant and Equipment, Including Asset Under Construction [Member] Property, Plant and Equipment, Including Asset Under Construction Contingent financial obligation Performance Guarantee [Member] Interest Expense Interest Expense [Member] Fair value of derivative instruments (Note 27) Derivative Liability, Noncurrent Increase (decrease) in Accrued interest Increase (Decrease) in Interest Payable, Net Metering and other Metering and Other [Member] Represents the long lived, depreciable other assets used for the primary purpose of measuring gas and liquids. Product and Service [Domain] Product and Service [Domain] Risk Management and Financial Instruments [Abstract] Risk Management and Financial Instruments [Abstract] Risk Management and Financial Instruments [Abstract] Interest on debt Interest Expense, Debt, Excluding Amortization Fair value of equity securities Equity Securities, FV-NI, Restricted One to two years Sales-Type and Direct Financing Leases, Payment to be Received, Year Two Continuing operations, Basic (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Consecutive period of employment for highest average earnings Defined Benefit Plan, Consecutive Period of Employment for Highest Average Earnings Represents the consecutive period of employment for highest average earnings for pension benefits provided under the defined benefit plans. Equity Attributable to Controlling Interests Parent [Member] Net Income (Loss) Net Income (Loss) Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Approved ROE on deemed common equity Approved Return on Equity Percentage Represents the percentage of return on equity approved by National Energy Board (NEB). Two to three years Lessor, Operating Lease, Payment to be Received, Year Three Business Combination [Table] Business Combination [Table] Total liabilities Liabilities, Fair Value Disclosure Notional Amount Notional amount Derivative, Notional Amount Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Unrealized actuarial gains (losses) on pension and other post-retirement benefit plans Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Equity allowance for funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Payments to be received Minimum lease payments Sales-Type and Direct Financing Leases, Payment to be Received City Area Code City Area Code Capitalized interest Interest Costs Capitalized Senior Unsecured Notes Due September 2035 Senior Unsecured Notes Due September 2035 [Member] Senior Unsecured Notes Due September 2035 US$ denominated United States of America, Dollars Net cash (used in) provided by investing activities Cash Provided by (Used in) Investing Activity, Discontinued Operation Power generation and natural gas storage plant, equipment and structures Energy Equipment [Member] Schedule of Contract Balances Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] JUNIOR SUBORDINATED NOTES Junior Subordinated Notes Disclosure [Text Block] The entire disclosure for junior subordinated notes, which have a lower priority than senior instruments. Disclosure may include maturity period and effective interest rate. Net Deferred Income Tax Liabilities Deferred Tax Liabilities, Net Past due or impaired Accounts Receivable, Past Due Or Impaired, Amount Accounts Receivable, Past Due Or Impaired, Amount Maturing December 2026 Unsecured Credit Facility Maturing December 2026 [Member] Unsecured Credit Facility Maturing December 2026 Fair Value Hedges Fair Value Hedging [Member] Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 2 [Member] Senior Unsecured Notes Due October 2024 2 Gain to be reclassified within twelve months Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months, Net Of Tax Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months, Net Of Tax Company debt or common shares included in plan assets, percentage Defined Benefit Plan, Amount of Employer and Related Party Securities Included in Plan Assets Percentage The percentage of employer securities or securities of parties related to the employer that are included in plan assets. Junior subordinated debt due 2085 Junior Subordinated Debt, Due 2085 [Member] Junior Subordinated Debt, Due 2085 Junior subordinated debt, due 2077 Junior Subordinated Debt, Due 2077 1 [Member] Junior Subordinated Debt, Due Two Thousand Seventy Seven [Member] Effective Income Tax Rate Reconciliation [Line Items] Effective Income Tax Rate Reconciliation [Line Items] Net operating lease cost Lease, Cost Cash Flow Hedges Cash Flow Hedging [Member] Natural Gas Power Generation Natural Gas Natural Gas [Member] Goodwill (Note 13) Balance at the beginning of the period Balance at the end of the period Goodwill Goodwill Schedule of Operating Lease Cost Lease, Cost [Table Text Block] Funding commitment Funding Commitment, Subordinated Loan Agreement Funding Commitment, Subordinated Loan Agreement Proceeds from sale of interest in partnership unit Proceeds from Sale of Interest in Partnership Unit Disallowed interest carryforward Deferred Tax Asset, Interest Carryforward Gain on sale, after tax Gain (Loss) on Sale of Subsidiary, Net of Tax Gain (Loss) on Sale of Subsidiary, Net of Tax Canada - federal Deferred Federal Income Tax Expense (Benefit) Unrecognized Tax Benefits [Roll Forward] Unrecognized Tax Benefits [Roll Forward] Auditor Name Auditor Name Schedule of Retired Long-Term Debt Schedule Of Long-Term Debt, Retired [Table Text Block] Schedule of Long-Term Debt, Retired [Table Text Block] DESCRIPTION OF TC ENERGY'S BUSINESS Nature of Operations [Text Block] Period one Period One [Member] Period One [Member] Long-Term Debt (Note 19) Noncurrent portion of long-term debt Other Long-Term Debt, Noncurrent Estimated future benefit payments, which reflect expected future service Defined Benefit Plan, Expected Future Benefit Payment [Abstract] Regulatory liability, amortization period Regulatory Liability, Amortization Period Foreign federal and state operating losses Operating Loss Carryforwards, Foreign, Federal And State Operating Loss Carryforwards, Foreign, Federal And State Reclassification to net income of actuarial (gains) losses on pension and other post-retirement benefit plans Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Balance at beginning of year Balance at end of year Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Medium Term Notes Due February 2026 Medium Term Notes Due February 2026 [Member] Medium Term Notes Due February 2026 Operating losses Operating Loss Carryforwards, Valuation Allowance Fixed Income Securities, International, Corporate Debt Security, Corporate, International [Member] Debt Security, Corporate, International [Member] Senior Unsecured Notes due June 2030 Senior Unsecured Notes Due June 2030 [Member] Senior Unsecured Notes Due June 2030 Fixed Income Securities, U.S. Bonds, Federal US Treasury and Government [Member] Weighted Average Exercise Prices Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Portion amortized out of AOCI and into net income Defined Benefit Plan, Net Actuarial Gains (Losses), Portion Amortized Out Of AOCI And Into Net Income Defined Benefit Plan, Net Actuarial Gains (Losses), Portion Amortized Out Of AOCI And Into Net Income Foreign currency translation gains and losses on net investment in foreign operations Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Southeast Gateway Pipeline Southeast Gateway Pipeline [Member] Southeast Gateway Pipeline Less than one year Lessor, Operating Lease, Payment to be Received, Year One Employee Post-Retirement Benefits Pension and Other Postretirement Plans, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] Amount Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] GREAT LAKES GAS TRANSMISSION LIMITED PARTNERSHIP Great Lakes Gas Transmission Limited Partnership [Member] Represents information pertaining to Great Lakes Gas Transmission Partnership, a natural gas transmission system that connects to the Canadian Mainline and serves markets in eastern Canada and the northeastern and midwestern United States. Derivative Instrument [Axis] Derivative Instrument [Axis] Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Debentures Due April 2023 Debentures Due April 2023 [Member] Debentures Due April 2023 Other current assets (Note 7) Other current assets Other current assets Other Assets, Current Deferred income taxes (Note 18) Deferred Income Tax Expense (Benefit), Including Discontinued Operations Deferred Income Tax Expense (Benefit), Including Discontinued Operations Entity [Domain] Entity [Domain] Net cash (used in) provided by investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Future revenues, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Fair value of derivative instruments (Note 27) Derivative Asset, Noncurrent Interest payments, net of interest capitalized Interest Paid, Excluding Capitalized Interest, Operating Activity Schedule of Weighted Average Asset Allocations and Target Allocations by Asset Category Schedule of Weighted Average and Target Allocation of Plan Assets [Table Text Block] Tabular disclosure of the weighted average asset allocations and the target allocations of plan assets by asset category for the defined benefit pension plan. Document Fiscal Year Focus Document Fiscal Year Focus Discount of shares issued from treasury Stock Issued During Period, Dividend Reinvestment Plan, Shares Issued From Treasury, Discount, Percent Stock Issued During Period, Dividend Reinvestment Plan, Shares Issued From Treasury, Discount, Percent Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Audited Annual Financial Statements Audited Annual Financial Statements Lender Name [Axis] Lender Name [Axis] Right-of-use asset Operating Lease, Right-of-Use Asset COMMON SHARES Shareholders' Equity and Share-Based Payments [Text Block] Deferred Costs, Noncurrent [Abstract] Deferred Costs, Noncurrent [Abstract] Income Tax Expense Effective Income Tax Rate Reconciliation, Percent Gross decrease - tax positions in prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Operating lease cost Operating Lease, Cost Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Contributions to equity investments (Notes 5 and 10) Payment to reduce company's funding commitment Payment to Acquire Equity Method Investments, Including Discontinued Operations Payment to Acquire Equity Method Investments, Including Discontinued Operations Cash Generated from Operations Cash Provided by (Used in) Operating Activity, Continuing Operation [Abstract] Carrying Amount Reported Value Measurement [Member] Net Investment in Leases (Note 9) Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss, Noncurrent Expense recognition period Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Exercise of options (in shares) Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Less: Valuation allowance Valuation allowance Deferred Tax Assets, Valuation Allowance Equity [Abstract] Equity [Abstract] Government of Canada, Treasury Bill Rate Government of Canada, 90-Day Treasury Bill Rate [Member] Government of Canada, 90-Day Treasury Bill Rate [Member] Non-taxable capital (gain) loss Effective Income Tax Rate Reconciliation, Non-Taxable Portion Of Capital Gains, Amount Effective Income Tax Rate Reconciliation, Non-Taxable Portion Of Capital Gains, Amount Senior Unsecured Notes Due October 2025 Senior Unsecured Notes Due October 2025 [Member] Senior Unsecured Notes Due October 2025 Derivative Instruments and Hedging Activities Derivatives, Policy [Policy Text Block] SEGMENTED INFORMATION Segment Reporting Disclosure [Text Block] Goodwill [Table] Goodwill [Table] Fair Value Hierarchy Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Period three Period Three [Member] Period Three [Member] Schedule of Amounts Recognized in the Balance Sheet for its DB Plans and Other Post-Retirement Benefits Plans Schedule of Amounts Recognized in Balance Sheet [Table Text Block] Plan assets at fair value – beginning of year Plan assets at fair value – end of year Plan assets at fair value Fair value of plan assets Defined Benefit Plan, Plan Assets, Amount Canada - federal Current Federal Tax Expense (Benefit) Amount Increase (Decrease) in Stockholders' Equity [Roll Forward] Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Axis] Purchases Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Other investments Other Debt Obligations [Member] Stated interest rate, period of time Debt Instrument, Interest Rate, Stated Percentage, Period of Time Debt Instrument, Interest Rate, Stated Percentage, Period of Time Senior Unsecured Notes Due June 2025 Senior Unsecured Notes Due June 2025 [Member] Senior Unsecured Notes Due June 2025 OTHER COMPREHENSIVE INCOME(LOSS) AND ACCUMULATED OTHER COMPREHENSIVE INCOME(LOSS) Comprehensive Income (Loss) Note [Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Commodity purchases resold Disposal Group, Including Discontinued Operation, Costs of Goods Sold Lessee Accounting Policy Lessee, Leases [Policy Text Block] Gas transportation and exchange payable Gas Purchase Payable, Current Cash provided as collateral Restricted Cash and Cash Equivalent, Current Redemption of shares Stock Redeemed or Called During Period, Value Expected credit loss provision Net Investment in Lease, Credit Loss Expense (Reversal) Deferred income tax assets (Note 18) Other long-term assets (Note 14) Deferred Income Tax Assets, Net Capital Spending Payments to Acquire Productive Assets Schedule of Changes in Accumulated Other Comprehensive Income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Annual dividend ( in Canadian dollars per share) Preferred Stock, Dividend Rate, Per-Dollar-Amount Depreciation and amortization Depreciation, Depletion and Amortization Net income (loss) attributable to common shares from continuing operations Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic Before Tax Amount Other Comprehensive Income (Loss), before Tax [Abstract] Investments of regulated natural gas pipelines (in miles) Public Utilities, Property, Plant and Equipment, Regulated Natural Gas Pipelines, in Miles Public Utilities, Property, Plant and Equipment, Regulated Natural Gas Pipelines, in Miles Company's expected funding contributions for savings plan and DC Plans Defined Contribution Savings and Other Postretirement Benefit Plans Estimated Future Employer Contributions in Next Fiscal Year The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the defined contribution, savings and other post-retirement benefit plans during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions. Revolving credit facility Revolving Credit Facility [Member] Rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Senior Unsecured Notes Due September 2031 Senior Unsecured Notes Due September 2031 [Member] Senior Unsecured Notes Due September 2031 Sales-type lease, net investment in lease, before allowance for credit loss Sales-Type Lease, Net Investment in Lease, after Allowance for Credit Loss Senior Unsecured Notes Due August 2028 Senior Unsecured Notes Due August 2028 [Member] Senior Unsecured Notes Due August 2028 Segments [Axis] Segments [Axis] TGNH TGNH Pipelines [Member] TGNH Pipelines Impact of non-controlling interest Other Comprehensive Income, Other, Net of Tax Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Local Phone Number Local Phone Number Long-term contract assets (Note 14) Contract assets (Note 6) Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent Deferred amounts and other Payment for (Proceeds from) Other Investing Activity Medium Term Notes Due November 2055 Medium Term Notes Due November 2055 [Member] Medium Term Notes Due November 2055 South Bow South Bow [Member] South Bow Deferred Income Tax Liabilities Deferred Tax Liabilities, Deferred Expense [Abstract] ASSETS Assets [Abstract] Credit Facility [Axis] Credit Facility [Axis] Senior Unsecured Notes Due October 2024 Senior Unsecured Notes Due October 2024 1 [Member] Senior Unsecured Notes Due October 2024 1 Senior Unsecured Revolving Credit Facility Various 2024 Senior Unsecured Revolving Credit Facility Various 2024 [Member] Senior Unsecured Revolving Credit Facility Various 2024 Net benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Debt Instrument [Axis] Debt Instrument [Axis] EMPLOYEE POST-RETIREMENT BENEFITS Retirement Benefits [Text Block] Business Combination [Line Items] Business Combination [Line Items] Interest rate Fixed Income Interest Rate [Member] Gain on debt extinguishment Gain (Loss) on Extinguishment of Debt Credit Facility [Domain] Credit Facility [Domain] Fair value of derivative instruments (Note 27) Derivative Liability, Current Canadian Mainline short-term adjustment and toll-stabilization accounts Canadian Mainline Short-Term Adjustment And Toll-Stabilization Accounts [Member] Canadian Mainline Short-Term Adjustment And Toll-Stabilization Accounts Income (Loss) from Discontinued Operations before Income Taxes Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax Notional amount, life (in years) Derivative, Nonmonetary Notional Amount, Life Derivative, Nonmonetary Notional Amount, Life Coastal GasLink Coastal GasLink Pipeline Limited Partnership [Member] Coastal GasLink Pipeline Limited Partnership Allowance for funds used during construction Allowance for funds used during construction Public Utilities, Allowance for Funds Used During Construction, Additions Interest Rate Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Investment, Name [Axis] Investment, Name [Axis] Canadian Mainline Canadian Mainline [Member] Represents information pertaining to Canadian Mainline, a natural gas transmission system extending from the Alberta/Saskatchewan border east into Quebec. Operating lease, reported as other long-term liabilities Operating lease liabilities (Note 9) Operating Lease, Liability, Noncurrent Sur de Texas Sur de Texas Transmission System [Member] Sur de Texas Transmission System [Member] Fixed Income Securities, Canadian Bonds, Provincial Defined Benefit Plan, Canadian Provincial Debt Securities [Member] Defined Benefit Plan, Canadian Provincial Debt Securities [Member] Balance Sheet Balance Sheet Related Disclosures [Abstract] Accumulated foreign currency adjustment attributable to noncontrolling interest Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest [Member] Contingencies Accrual for Environmental Loss Contingencies [Abstract] Intangible Assets, Net (Excluding Goodwill) [Abstract] Intangible Assets, Net (Excluding Goodwill) [Abstract] Natural Gas Pipelines Natural Gas Pipelines Segment [Member] Represents information pertaining to the Natural Gas Pipelines segment of the entity which consists of the Company's investment in regulated natural gas pipelines and regulated natural gas storage facilities. Gross Derivative Instruments Derivative Liability, Not Subject to Master Netting Arrangement COMMITMENTS, CONTINGENCIES AND GUARANTEES Commitments Contingencies and Guarantees [Text Block] Derivative Assets Derivative Instrument Assets Derivative Asset, Subject to Master Netting Arrangement, before Offset Property, Plant and Equipment [Abstract] Entity Registrant Name Entity Registrant Name Cash flow hedge gain reclassified within twelve months Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months Senior Unsecured Notes due November 2021 Senior Unsecured Notes Due February 2024 [Member] Senior Unsecured Notes Due February 2024 Net Benefit Cost Recognized Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Conversion ratio Conversion Of Stock, Conversion Ratio Conversion Of Stock, Conversion Ratio Liabilities Disposal Group, Including Discontinued Operation, Liabilities Foreign exchange rate changes Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) Trading Activity [Axis] Trading Activity [Axis] Income from equity investments Effective Income Tax Rate Reconciliation, Equity Investments, Amount Effective Income Tax Rate Reconciliation, Equity Investments, Amount Regulated Operations [Abstract] Regulated Operations [Abstract] Regulatory and other deferred amounts Deferred Tax Assets, Regulatory Assets and Liabilities ANR ANR PIPELINE COMPANY ANR Pipe Line Company [Member] Represents information pertaining to ANR PipeLine Company. Expected credit loss provision (Note 27) Provision for Loan, Lease, and Other Losses Energy [Axis] Energy [Axis] Number of business segments in which the entity operates (in segments) Number of Operating Segments Tax Credit Carryforward [Line Items] Tax Credit Carryforward [Line Items] Interest cost Defined Benefit Plan, Interest Cost Northern Border Northern Border Pipeline Company [Member] Represents information pertaining to Northern Border Pipeline Company. Related Party [Axis] Related and Nonrelated Parties [Axis] Medium Term Notes Due July 2025 Medium Term Notes Due July 2025 [Member] Medium Term Notes Due July 2025 Pre-tax amounts recognized in AOCI Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract] Other long-term liabilities Other Noncurrent Liabilities [Member] $800 notes due 2082 at 5.85% Junior Subordinated Notes Due 2082 [Member] Junior Subordinated Notes Due 2082 DB Plans Defined Benefit Plan, Expected Future Employer Contributions [Abstract] Foreign Deferred Foreign Income Tax Expense (Benefit) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Amortization of net gain (loss) from AOCI to net income Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax Restricted Investments Restricted Investments Reclassification from accumulated other comprehensive income (loss) Amounts reclassified from AOCI Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax All Currencies [Domain] All Currencies [Domain] Regulatory Asset [Axis] Regulatory Asset [Axis] Fixed Income Securities, U.S. Bonds, Municipal US States Municipal Debt Securities [Member] US States Municipal Debt Securities [Member] Schedule of Short-term Debt [Table] Short-Term Debt [Table] Purchase commitment Long-Term Purchase Commitment, Amount Series 8 Series Eight [Member] Series 8 [Member] Series 5 Series Five Preferred Stock [Member] Represents information pertaining to the Series 5 cumulative preferred stock. Debt instrument, face amount Amount Debt Instrument, Face Amount Gain (loss) on cash flow hedge Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net Reclassification of foreign currency translation (gains) losses on net investment on disposal of foreign operations Accumulated Foreign Currency Adjustment Attributable to Disposal of Foreign Operations [Member] Accumulated Foreign Currency Adjustment Attributable to Disposal of Foreign Operations Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Income (Loss) from Equity Investments Disposal Group, Including Discontinued Operation, Income (Loss) from Equity Investments Disposal Group, Including Discontinued Operation, Income (Loss) from Equity Investments Plant operating costs and other Operating Costs and Expenses Medium Term Notes Due February 2035 Medium Term Notes Due February 2035 [Member] Medium Term Notes Due February 2035 Preferred Shares (Note 24) Preferred Stock [Member] Valuation Allowance Carryforward, Valuation Allowance [Member] Carryforward, Valuation Allowance Income tax expense (recovery) Discontinued Operation, Tax Effect of Discontinued Operation Weighted average actuarial assumptions adopted in measuring the net benefit plan costs Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Equity investments Equity Funds [Member] ACCOUNTS PAYABLE AND OTHER Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Energy [Domain] Energy [Domain] Long term adjustment account, amount to be amortized over one year Long Term Adjustment Account, Amount To Be Amortized Over Settlement Term [Member] Long Term Adjustment Account, Amount To Be Amortized Over Settlement Term Unused Amounts Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract] Regulatory Assets (Note 12) Regulatory Assets, noncurrent Regulatory Assets Regulatory Asset, Noncurrent Other comprehensive income (loss) attributable to non-controlling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Schedule of Non-controlling Interests Schedule of Noncontrolling Interest [Table Text Block] Schedule of Noncontrolling Interest [Table Text Block] Other current assets Disposal Group, Including Discontinued Operation, Other Assets, Current Other comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss) before Reclassifications, Tax Liability Class [Axis] Liability Class [Axis] Loan from affiliate (Note 11) Advances From Affiliate Advances From Affiliate Disposition of equity interest, net of transaction costs (Note 29) Adjustments to Additional Paid in Capital, Disposition Of Non Controlling Interests Adjustments to Additional Paid in Capital, Disposition Of Non Controlling Interests Foreign Tax Jurisdiction Foreign Tax Jurisdiction [Member] Auditor Firm ID Auditor Firm ID Medium Term Notes due June 2024 Medium Term Notes Due June 2024 [Member] Medium Term Notes Due June 2024 Segments [Domain] Segments [Domain] Damages sought Loss Contingency, Damages Sought, Value Statement of Income Location, Balance [Axis] Statement of Income Location, Balance [Axis] Defined Benefits, Contribution And Other Postretirement Plan Contributions [Abstract] Defined Benefits, Contribution And Other Postretirement Plan Contributions [Abstract] Defined Benefits, Contribution And Other Postretirement Plan Contributions [Abstract] Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Non-current assets Assets, Noncurrent Unused capacity Line of Credit Facility, Remaining Borrowing Capacity Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Benefit obligation – beginning of year Benefit obligation – end of year Projected benefit obligation Defined Benefit Plan, Benefit Obligation Unused Amounts Carryforward, Unused Amount [Member] Carryforward, Unused Amount (Increase) decrease in Inventories Increase (Decrease) in Inventories Statement of Financial Position Location, Balance [Domain] Statement of Financial Position Location, Balance [Domain] Foreign exchange on long-term debt Foreign Exchange on Long Term Debt [Member] Represents information pertaining to the foreign exchange on long-term debt as a regulatory liability. Amortization and other financial charges Amortization of Debt Issuance Costs and Discounts Cash collateral received by the Company (less than) Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Equity investments AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Interest Expense, Operating and Nonoperating [Abstract] Interest Expense, Operating and Nonoperating [Abstract] Accumulated Depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Assets Held For Sale Assets, Held For Sale, Policy [Policy Text Block] Assets, Held For Sale, Policy Capital projects in development (Note 5) Capital projects in development Payments for Construction in Process Senior notes Senior Notes [Member] Amounts Available for Offset Derivative Liability, Subject to Master Netting Arrangement, Asset Offset Preferred shares (Note 24) Preferred shares Preferred Stock, Value, Issued Fair value Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Preferred shares redeemed (Note 24) Payments for Repurchase of Redeemable Preferred Stock Interest expense after interest allocated to discontinuing operations Interest Expense, Before Discontinued Operations Interest Expense, Before Discontinued Operations Subordinated debt Subordinated Debt [Member] Columbia Pipeline Group shareholders Columbia Pipeline Group, Shareholders [Member] Columbia Pipeline Group, Shareholders Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets Defined Benefit Plan, Plan with Projected Benefit Obligation in Excess of Plan Assets [Table Text Block] Schedule of Deferred Income Tax Assets and Liabilities and Amounts Classified in the Consolidated Balance Sheet Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Common shares, no par value (Note 23) Outstanding at the beginning of the period Outstanding at the end of the period Common Stock, Value, Issued Derivatives designated as hedging instruments Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Operating Activities [Domain] Operating Activities [Domain] Schedule of Contributions for Defined Benefit Plans Schedule of Payments for Defined Benefit Plans [Table Text Block] Schedule of Payments for Defined Benefit Plans [Table Text Block] Income tax penalties accrued Income Tax Examination, Penalties Accrued Schedule of Realized Gain (Loss) on Investments Realized Gain (Loss) on Investments [Table Text Block] Business Combination [Axis] Business Combination [Axis] Comprehensive Income (Loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Schedule of Revenue from External Customers by Geographic Areas Revenue from External Customers by Geographic Areas [Table Text Block] Options Exercisable at December 31, 2020 (in Canadian dollars per share) Share-Based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price Equity Attributable to Non-Controlling Interests Noncontrolling Interest [Member] Sales-type lease, net investment in lease, before allowance for credit loss, noncurrent Sales-Type Lease, Net Investment in Lease, after Allowance for Credit Loss, Noncurrent Income from non-controlling interests Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount Ownership interest percentage Equity Method Investment, Ownership Percentage ACCOUNTING CHANGES Accounting Standards Update and Change in Accounting Principle [Text Block] Noncontrolling Interest [Table] Noncontrolling Interest [Table] More than five years Lessor, Operating Lease, Payment to be Received, after Year Five Notes payable Short-Term Debt [Line Items] Blue Cloud Wind Farm Blue Cloud Wind Farm [Member] Blue Cloud Wind Farm Risk management and financial instruments Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Maturing after 10 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Percentage of Plan Assets Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Long-term debt Hedged Liability, Fair Value Hedge Options forfeited/expired (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period Fair value adjustments of interest rate hedge Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Long-Term Debt, Hedged Interest Rate Risk Portion Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Long-Term Debt, Hedged Interest Rate Risk Portion Withholding tax Effective Income Tax Rate Reconciliation, Tax Settlement, Percent Maximum cost recovery and return on investment Regulatory Assets and Liabilities, Maximum Cost Recovery And Return on Investment Regulatory Assets and Liabilities, Maximum Cost Recovery And Return on Investment Reclassification of foreign currency translation (gains) losses on net investment on disposal of foreign operations Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax Schedule of Significant Weighted Average Actuarial Assumptions Adopted in Measuring Net Benefit Plan Costs Schedule of Assumptions used to Determine Net Periodic Benefit Cost [Table Text Block] Tabular disclosure of the assumptions used to determine, for pension plans and/or other employee benefit plans, the net periodic benefit cost, including assumed discount rates, expected long-term rates of return on plan assets and rate of compensation increase. Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Schedule of Derivative Instruments - Balance Sheet and Income Statement Information Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Fair value Debt Instrument, Fair Value Disclosure Schedule of Reconciliation of Unrecognized Tax Benefit Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Other Long-Term Assets Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent Non-Controlling Interests Non-Controlling Interests [Policy Text Block] Non-Controlling Interests Accounts payable and other (Note 16) Accounts payable and other Accounts payable and other Accounts Payable and Other Accrued Liabilities, Current Wind Generation Wind Generation [Member] Wind Generation Net Amounts Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Reclassification of gains/(losses) on derivative instruments from AOCI to net income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Designated as a net investment hedge Net Investment Hedges Net Investment Hedging [Member] Derivative Contract [Domain] Derivative Contract [Domain] Common shares issued, net of issue costs Proceeds from Issuance of Common Stock 2030 Defined Benefit Plan, Expected Future Benefit Payment, Year Five Unrealized Foreign Exchange on Long-Term Debt Deferred Tax Assets, Unrealized Foreign Exchange On Long-Term Debt Deferred Tax Assets, Unrealized Foreign Exchange On Long-Term Debt Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Senior Unsecured Revolving Credit Facility Due January 2028 Senior Unsecured Revolving Credit Facility Due January 2028 [Member] Senior Unsecured Revolving Credit Facility Due January 2028 Net cash (used in) provided by operations Cash Provided by (Used in) Operating Activity, Discontinued Operation Operating lease termination period Lessee, Operating Lease, Termination Period Lessee, Operating Lease, Termination Period Amounts reclassified from AOCI Reclassification out of Accumulated Other Comprehensive Income [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Senior Unsecured Notes Due March 2025 Senior Unsecured Notes Due March 2025 [Member] Senior Unsecured Notes Due March 2025 Foreign exchange Foreign Exchange [Member] Foreign exchange rate changes Goodwill, Foreign Currency Translation, Gain (Loss) Options expiration term Share Based Compensation Arrangements by Share Based Payment Award Options Expiration Term The period of time, from the grant date until the time at which the share-based (option) award expires. Investments of regulated natural gas storage facilities (in billion cubic feet) Public Utilities, Property, Plant and Equipment, Regulated Natural Gas Storage Facilities, in Billion Cubic Feet Public Utilities, Property, Plant and Equipment, Regulated Natural Gas Storage Facilities, in Billion Cubic Feet Equity securities Defined Benefit Plan, Equity Securities [Member] Schedule of Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Geographical [Axis] Geographical [Axis] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Senior Unsecured Notes Due February 2035 Senior Unsecured Notes Due February 2035 [Member] Senior Unsecured Notes Due February 2035 Coastal GasLink Coastal GasLink Pipeline Project [Member] Coastal GasLink Pipeline Project [Member] TC PIPELINES, LP TC PIPELINES, LP TC Pipe Lines LP [Member] Represents information pertaining to TC PipeLines, LP. Minimum tax Deferred Tax Assets, Tax Credit Carryforwards Foreign exchange (gains) losses, net (Note 21) Foreign exchange gains (losses), net Foreign exchange (gains) losses Gain (Loss), Foreign Currency Transaction, before Tax LEASES Lessor, Operating Leases [Text Block] Medium Term Notes Due March 2026 Medium Term Notes Due March 2026 [Member] Medium Term Notes Due March 2026 Capital loss Deferred Tax Assets, Capital Loss Carryforwards Title of 12(b) Security Title of 12(b) Security Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Senior Unsecured Notes Due March 2026 Senior Unsecured Notes Due March 2026 [Member] Senior Unsecured Notes Due March 2026 Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Employer contributions Defined Benefit Plan, Plan Assets, Contributions by Employer, Reduced By Funding Defined Benefit Plan, Plan Assets, Contributions by Employer, Reduced By Funding Capacity arrangements and transportation Capacity Arrangements And Transportation [Member] Capacity Arrangements And Transportation [Member] Equity Investments Equity Method Investments, Valuation Allowance Equity Method Investments, Valuation Allowance Issuance of stock options, net of exercises APIC, Share-Based Payment Arrangement, Option, Increase for Cost Recognition Net Income (Loss) per Common Share - Basic and Diluted (Note 23) Earnings Per Share [Abstract] Shares converted (in shares) Conversion of Stock, Shares Converted Four to five years Lessee, Operating Lease, Liability, to be Paid, Year Five Noncontrolling interests ownership Subsidiary, Ownership Percentage, Parent Other distributions from equity investments (Note 10) Proceeds from Equity Method Investment, Distribution, Return of Capital Number of electrical power generation plants (in plants) Public Utilities, Property, Plant and Equipment, Number of Electrical Power Generation Plants Public Utilities, Property, Plant and Equipment, Number of Electrical Power Generation Plants Income tax differential related to regulated operations Effective Income Tax Rate Reconciliation, Related to Regulated Operations, Percent Effective Income Tax Rate Reconciliation, Related to Regulated Operations, Percent Gain on sale, before tax Gain (Loss) on Sale of Subsidiary, Before Tax Gain (Loss) on Sale of Subsidiary, Before Tax Fluvanna Wind Farm Fluvanna Wind Farm [Member] Fluvanna Wind Farm Minimum tax Tax Credit Carryforward, Amount Provision for other credit losses Provision for Other Credit Losses Balance Sheet Exposure Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure [Abstract] Purchases and sales Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Purchase, Sale, and Settlement Short-term Debt, Type [Axis] Short-Term Debt, Type [Axis] Under construction Asset under Construction [Member] Additional aggregate cost Equity Method Investment, Additional Income Equity Method Investment, Additional Income Fair value of securities Debt and Equity Securities, Available-for-sale Debt and Equity Securities, Available-for-sale Impact of non-controlling interest (Note 29) Adjustments to Additional Paid in Capital, Impact of Non Controlling Interest Adjustments to Additional Paid in Capital, Impact of Non Controlling Interest Accounts payable and other Accounts Payable and Accrued Liabilities [Member] Recognition of the settlement a net loss from discontinued operations Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation Difference in accounting and tax bases of plant, property and equipment Deferred Tax Liabilities Property Plant and Equipment and Intangible Assets Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment and intangible assets other than goodwill. Exercised (in Canadian dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Equity Contribution Agreement Equity Contribution Agreement [Member] Equity Contribution Agreement Service cost Defined Benefit Plan, Service Cost Measurement Frequency [Domain] Measurement Frequency [Domain] Operating leases optional renewable terms Lessee, Operating Lease, Renewal Term Impairment of equity investment (Note 10) Impairment of equity investment (Note 10) Impairment From Equity Method Investments Impairment From Equity Method Investments Other comprehensive income/(loss), before reclassifications Other comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Long-term debt issued, net of issue costs Proceeds from Issuance of Other Long-Term Debt Unearned lease income Sales-Type and Direct Financing Leases, Unearned Lease Income Sales-Type and Direct Financing Leases, Unearned Lease Income Net Income (Loss) Attributable to Controlling Interests Net income (loss) attributable to controlling interests Net income Net Income (Loss) Attributable to Parent Other post-retirement benefit plans, Savings Plan and DC Plans Defined Contribution Savings and Other Postretirement Benefit Plans Disclosure [Abstract] 143e3ae0-53cd-11e3-b035-22000a1e8102 Canadian provincial taxes Effective Income Tax Rate Reconciliation at Canada Provincial Income Tax Rate, Amount Effective Income Tax Rate Reconciliation at Canada Provincial Income Tax Rate, Amount Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee [Domain] Fixed portion of the operating lease income Operating Lease, Lease Income, Lease Payments Other Other Accrued Liabilities, Current Discontinued operations, Basic (in dollars per share) Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share Schedule of Reconciliation of Income Tax Expense Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Award vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Interest expense Disposal Group, Including Discontinued Operation, Interest Expense Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent OTHER CURRENT ASSETS Other Current Assets [Text Block] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Senior Unsecured Notes Senior Unsecured Notes [Member] Represents information pertaining to the senior unsecured notes. Contributions from non-controlling interests Noncontrolling Interest, Contribution From Parent, Capital Maintenance And Servicing Noncontrolling Interest, Contribution From Parent, Capital Maintenance And Servicing Tax Credit Carryforward [Table] Tax Credit Carryforward [Table] Regulation Disclosure Of Accounting Policy For Rate Regulated Natural Gas Pipelines [Policy Text Block] Disclosure of accounting policy for rate regulated natural gas pipelines [Policy Text Block] [Policy Text Block] Financing Activities Cash Provided by (Used in) Financing Activity, Continuing Operation [Abstract] Segmented Earnings (Losses) Operating Income (Loss) Line of credit Line of Credit [Member] Schedule of Offsetting Liabilities Offsetting Liabilities [Table Text Block] Other comprehensive income (loss) on equity investments Equity investments AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Including Noncontrolling Interest [Member] Retained earnings (Accumulated deficit) Retained Earnings (Accumulated Deficit) Schedule of Change in Benefit Obligations, Change in Plan Assets, and Funded Status Schedule of Net Funded Status [Table Text Block] U.S. dollar cross-currency interest rate swaps (maturing 2025) Cross Currency Interest Rate Contract [Member] Reclassification of net investment hedge losses from AOCI to non-controlling interests (NCI) related to the sale Reclassification of net investment hedge losses from AOCI to non-controlling interests (NCI) related to the sale Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), Reclassification, before Tax Senior Unsecured Notes Due February 2055 Senior Unsecured Notes Due February 2055 [Member] Senior Unsecured Notes Due February 2055 Fixed Income Securities, Canadian Bonds, Municipal Defined Benefit Plan, Canadian Municipal Debt Securities [Member] Defined Benefit Plan, Canadian Municipal Debt Securities [Member] Medium Term Notes Due May 2025 Medium Term Notes Due May 2025 [Member] Medium Term Notes Due May 2025 Class of Stock [Axis] Class of Stock [Axis] Cash flow hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Environmental Liabilities and Emission Allowances and Credits Environmental Costs, Policy [Policy Text Block] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Long-term debt, weighted average discount, percent Long-term Debt, Weighted Average Discount, Percent Long-term Debt, Weighted Average Discount, Percent Equity Securities, Canadian Defined Benefit Plan, Equity Securities, Canada [Member] Defined Benefit Plan, Equity Securities, Canada [Member] Other Deferred Tax Liabilities, Other Current liabilities of discontinued operations (Note 4) Current liabilities of discontinued operations (Note 4) Disposal Group, Including Discontinued Operation, Liabilities, Current Retirement Plan Type [Axis] Retirement Plan Type [Axis] Payables and Accruals [Abstract] Payables and Accruals [Abstract] Interest income and other Interest income and other Other Nonoperating Income (Expense) Statement [Table] Statement [Table] Actual return on plan assets Realized and unrealized gains (losses) Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Deferred Total Deferred Income Tax Expense (Benefit) Lapse of statutes of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Other foreign jurisdictions Foreign Tax Jurisdiction, Other [Member] Fixed Income Securities, International, Government Debt Security, Government, International [Member] Debt Security, Government, International [Member] Segmented information Segment Reporting Information, Profit (Loss) [Abstract] Sales-Type Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration] Sales-Type Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration] Fixed Income Securities, International, Mortgage-backed Collateralized Mortgage Backed Securities, International [Member] Collateralized Mortgage Backed Securities, International [Member] Variable Rate [Domain] Variable Rate [Domain] Proceeds from incentive fees Proceeds From Incentive Fees Proceeds From Incentive Fees Lessor Accounting Policy Lessor, Leases [Policy Text Block] Pre tax separation, before reclassification Spinoff Transaction, Separation Transaction Costs, Before Tax Spinoff Transaction, Separation Transaction Costs, Before Tax Minimum tax Tax Credit Carryforward, Valuation Allowance Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Amendment Flag Amendment Flag Pipeline Pipelines [Member] Other Post-Retirement Benefit Plans Other Postretirement Benefits Plan [Member] Senior Unsecured Notes Due November 2033 Senior Unsecured Notes Due November 2033 [Member] Senior Unsecured Notes Due November 2033 Less than one year Sales-Type and Direct Financing Leases, Payment to be Received, Year One Pre-tax gain on the debt extinguishment Extinguishment of Debt, Gain (Loss), Income Tax Other Long-Term Liabilities Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent Period of Government of Canada bond or treasury bill considered for calculation of dividend yield per annum Preferred Stock Period of Treasury Bill Considered for Dividend Yield Calculation Represents the period of treasury bill considered for calculation of dividend yield per annum. Junior subordinated debt, due 2056 Junior Subordinated Debt, Due 2056 [Member] Junior Subordinated Debt, Due 2056 Weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Schedule of Stock Options Activity Share-Based Payment Arrangement, Option, Activity [Table Text Block] Texas Wind Farms Texas Wind Farms [Member] Texas Wind Farms Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Unrealized foreign exchange losses on long-term debt Deferred Tax Assets, Unrealized Currency Losses Options Exercisable (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Segment Reporting [Abstract] Segment Reporting [Abstract] Other Other Regulatory Liabilities [Member] Represents the regulatory liabilities arising from other regulatory matters not specified in the taxonomy. Debt Disclosure [Abstract] Debt Disclosure [Abstract] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Operating and Other Expenses Costs and Expenses [Abstract] Reclassification from AOCI Reclassification from AOCI, Current Period, Tax Other Natural Gas Pipelines Other Natural Gas Pipelines [Member] Represents information pertaining to natural gas transmission system other than Canadian Mainline, Alberta System and ANR. Foreign exchange (gains) losses, net – intercompany loan Foreign Currency Transaction Gain (Loss) On Loan Receivable Foreign Currency Transaction Gain (Loss) On Loan Receivable Net realized (losses)/ gains Debt Securities, Available-for-Sale, Realized Gain (Loss) Interest (recovery) expense reflected within net tax expense Unrecognized Tax Benefits, Interest on Income Taxes Expense Consolidated Entities [Axis] Consolidated Entities [Axis] Equity Investments Equity Investments, Carryforwards Equity Investments, Carryforwards Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Period of time preferred stock or bond is considered for dividend yield calculation Preferred Stock Period of Bond Considered for Dividend Yield Calculation Preferred Stock Period of Bond Considered for Dividend Yield Calculation Reclassification of additional paid-in capital deficit to accumulated deficit Adjustments To Additional Paid In Capital, Reclassification Of Additional Paid-In Capital Deficit To Retained Earnings Adjustments To Additional Paid In Capital, Reclassification Of Additional Paid-In Capital Deficit To Retained Earnings 2031 to 2035 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Schedule of changes in operating working capital Cash Flow, Operating Capital [Table Text Block] Number of legal entities (in subsidiaries) Number Of Legal Entities Number Of Legal Entities Net unrealized gains (losses) Debt Securities, Available-for-Sale, Unrealized Gain (Loss) Effect of cross-border taxes Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Amount Line of credit facility, outstanding amount Line of Credit Facility, Fair Value of Amount Outstanding Use of Estimates and Judgments Use of Estimates, Policy [Policy Text Block] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Regulatory Assets Regulatory Asset Subordinated Loan Agreement Subordinated Loan Agreement [Member] Subordinated Loan Agreement Address Type [Domain] Address Type [Domain] Sale of equity, noncontrolling interest Sale Of Equity, Noncontrolling Interest Sale Of Equity, Noncontrolling Interest Capital projects in development Construction in Progress, Gross ANR ANR PIPELINE COMPANY ANR [Member] Represents information pertaining to ANR, a natural gas transmission system extending from producing fields primarily located in Texas, Oklahoma, the Gulf of Mexico and Louisiana to markets primarily located in Wisconsin, Michigan, Illinois, Ohio and Indi Accounts payable and other Liability, Defined Benefit Pension Plan, Current Iroquois Iroquois Gas Transmission System LP [Member] Represents information pertaining to Iroquois Gas Transmission System, L.P. Amounts Available for Offset Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Less: Current portion included in Accounts payable and other (Note 16) Regulatory liabilities (Note 12) Regulatory Liability, Current Subordinated Demand Revolving Credit Facility Agreement Subordinated Demand Revolving Credit Facility Agreement [Member] Subordinated Demand Revolving Credit Facility Agreement Total liabilities Liabilities Currency [Axis] Currency [Axis] Pension plans' weighted average asset allocations and target allocations by asset category Defined Benefit Plan, Information about Plan Assets [Abstract] Distributions to non-controlling interests and other Payments of Ordinary Dividends, Noncontrolling Interest Net investment in lease Net Investment in Lease, Purchase Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Junior Subordinated Notes Due October 2025 Junior Subordinated Notes Due October 2025 [Member] Junior Subordinated Notes Due October 2025 Gross increase - tax positions in current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Schedule of Allocation of Plan Assets, Employer and Related Party Securities Schedule of Allocation of Plan Assets, Employer and Related Party Securities [Table Text Block] Schedule of Allocation of Plan Assets, Employer and Related Party Securities [Table Text Block] Company's expected funding contributions Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Offsetting Assets [Line Items] Offsetting Assets [Line Items] Letters of credit provided by the Company Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Security Not Offset Liquids Pipelines Segment Liquids Pipelines Segment [Member] Represents information pertaining to Liquids Pipelines segment of the entity. Variable Rate [Axis] Variable Rate [Axis] Senior Unsecured Notes Due October 2054 Senior Unsecured Notes Due October 2054 [Member] Senior Unsecured Notes Due October 2054 Consolidation Items [Axis] Consolidation Items [Axis] Health care benefits Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract] Counterparty Name [Axis] Counterparty Name [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Net Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position