Contributions by company to the plan
Defined Contribution Plan Employer Contribution Amount
Amount of contributions made by an employer to a defined contribution plan.
Target Allocation (as a percent)
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage
Long-Term Software/Meter Agreement [Member]
Long Term Software And Meter Agreement [Member]
Long term software and meter agreement.
Change in projected benefit obligation
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Estimated annual pension plan contributions for 2021
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year
Total other long-term assets
Assets, Noncurrent, Excluding Property, Plant And Equipment
Assets, Noncurrent, Excluding Property, Plant And Equipment
Option One [Member]
Option One [Member]
Option One [Member]
ABO [Member]
Accumulated Benefit Obligation [Member]
Accumulated Benefit Obligation [Member]
Financing charges (Notes 4, 6)
Net financing charges
Interest and Debt Expense
Related Party [Axis]
Related Party [Axis]
Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain]
Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain]
Change in plan assets
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Noncontrolling Interest [Table]
Noncontrolling Interest [Table]
Regulatory assets (Note 13)
Less: current portion
Regulatory Assets, Current
Summary of Other Commitments
Other Commitments [Table Text Block]
Environmental [Member]
Environmental Restoration Costs [Member]
Statistical Measurement [Domain]
Statistical Measurement [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Distributions to noncontrolling interest
Distributions to noncontrolling interest, equity
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders
Outsourcing and other agreements, Year 3
Outsourcing Agreements Future Minimum Payments Due in Third Year
Amount of required minimum payments under outsourcing agreements due in third year.
Preferred Stock [Member]
Preferred Stock [Member]
Pension and Post-Retirement and Post-Employment Benefits
Compensation and Employee Benefit Plans [Text Block]
Fair value of plan assets, beginning of year
Fair value of plan assets, end of year
Fair value of plan assets
Total fair value of plan assets
Defined Benefit Plan, Plan Assets, Amount
Debt instrument unused borrowing capacity
Debt Instrument, Unused Borrowing Capacity, Amount
Long-term debt issued
Proceeds from long-term debt offering
Proceeds from Issuance of Long-term Debt
Ownership, percentage
Ownership, Percentage
Ownership, Percentage
Total current liabilities
Liabilities, Current
2.57% Series 39 Notes Due 2021 [Member]
Two Point Five Seven Percent Series Thirty Nine Notes Due Two Thousand Twenty One [Member]
Two Point Five Seven Percent Series Thirty Nine Notes Due Two Thousand Twenty One [Member]
Other Revenue [Member]
Other Revenue [Member]
Other Revenue [Member]
Other commitments due
Other commitment, Year 1
Other Commitment, to be Paid, Year One
Prepaid expenses and other assets
Prepaid Expense and Other Assets, Current
Estimated annual pension plan contributions for 2025
2025
Defined Benefit Plan, Expected Future Benefit Payment, Year Five
Assets
Assets [Abstract]
Property, Plant and Equipment [Table]
Property, Plant and Equipment [Table]
Accounting Policies [Abstract]
Accounting Policies [Abstract]
Reconciling items, property plant and equipment
Capitalized Depreciation And Net Change In Accruals Included In Capital Investments In Property Plant And Equipment
Capitalized Depreciation And Net Change In Accruals Included In Capital Investments In Property Plant And Equipment
Due to related parties (Note 29)
Due to Related Parties, Current
Lease payments made
Operating Lease, Payments
Mississaugas of the Credit First Nation [Member]
Mississaugas Of The Credit First Nation [Member]
Mississaugas Of The Credit First Nation [Member]
Year 3
Long-Term Debt, Maturity, Year Three
Other Comprehensive Loss
Comprehensive Income (Loss) Note [Text Block]
Development in Progress
Finite Lived Intangible Assets Development In Progress
Finite Lived Intangible Assets Development In Progress
Total actuarial gains and losses and prior service costs
Recognition Of Actuarial Gains And Losses And Amortization Of Prior Service Cost
Recognition of actuarial gains and losses and amortization of prior service cost.
Gain (loss) on cash flow hedges (interest-rate swap agreements) (Notes 6, 18)
Unrealized (loss) gain on cash flow hedges, net of tax
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax
Entity Address, Country
Entity Address, Country
Repayment of short-term debt assumed
Repayments Of Assumed Debt, Short-Term
Repayments Of Assumed Debt, Short-Term
Environmental Liabilities [Line Items]
Environmental Liabilities [Line Items]
Environmental Liabilities [Line Items]
2021
2020
Lessee, Operating Lease, Liability, to be Paid, Year One
Corporate Shares - Foreign [Member]
Debt Security, Corporate, Non-US [Member]
Construction and Development in Progress
Construction In Progress [Policy Text Block]
Construction In Progress Policy [Text Block]
Outstanding, beginning (in shares)
Outstanding, ending (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number
2024
2023
Lessee, Operating Lease, Liability, to be Paid, Year Four
Loss Contingencies
Loss Contingencies [Policy Text Block]
Loss Contingencies [Policy Text Block]
Net income attributable to:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest [Abstract]
Province [Member]
Province Of Ontario [Member]
Province Of Ontario [Member]
Regulatory liabilities (Note 13)
Regulatory liabilities
Regulatory Liability, Noncurrent
Estimated annual pension plan contributions for 2023
2023
Defined Benefit Plan, Expected Future Benefit Payment, Year Three
Schedule of Depreciation and Amortization
Schedule Of Depreciation And Amortization [Table Text Block]
Schedule Of Depreciation And Amortization
Other long-term liabilities (Note 16)
Other long-term liabilities
Other Liabilities, Noncurrent
Deferred income tax assets
Deferred Income Tax Assets, Net
Costs
Cost of Revenue [Abstract]
Rate of increase in health care cost trends
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Health Care Cost Trend Rate
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Health Care Cost Trend Rate
Document Information [Table]
Document Information [Table]
Related party transaction amount
Related Party Transaction, Amounts of Transaction
Measurement Frequency [Domain]
Measurement Frequency [Domain]
Average remaining service life of employees (years)
Defined Benefit Plan Assumptions Used In Calculations Average Remaining Service Period
Defined benefit plan assumptions used in calculations average remaining service period.
Maximum amount contributed by employer
Defined Contribution Plan Maximum Annual Contributions Per Employer Amount
Defined contribution plan maximum annual contributions per employer amount.
Market Risk, Credit Risk And Liquidity Risk [Line Items]
Market Risk, Credit Risk And Liquidity Risk [Line Items]
Market Risk, Credit Risk And Liquidity Risk [Line Items]
Expiration period (in years)
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period
Statement [Line Items]
Statement [Line Items]
Management Deferred Share Units Plan [Member]
Management Deferred Share Units Plan [Member]
Management Deferred Share Units Plan [Member]
Class of Stock [Domain]
Class of Stock [Domain]
Subsequent Events (Note 34)
Subsequent Events
Subsequent Events
Tax Period [Axis]
Tax Period [Axis]
Maturities days of commercial paper
Debt instrument term (in months)
Debt Instrument, Term
Accounts Receivable
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]
Long-term software/meter agreement, Year 1
Long Term Software and Meter Agreement Future Minimum Payments Due in Next Twelve Months
Amount of required minimum payments under Long term software and meter agreement due in next twelve months.
Number of options vested with a modified fair value (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares
Statement [Table]
Statement [Table]
Less: Unamortized deferred debt issuance costs
Debt Issuance Costs, Current, Net
Write-offs
Accounts Receivable, Allowance for Credit Loss, Writeoff
Other
Other Comprehensive Income, Other, Net of Tax
Environmental liabilities non current portion
Environment Liabilities Non Current
Environment liabilities non current.
Interest cost
Defined Benefit Plan, Interest Cost
Statistical Measurement [Axis]
Statistical Measurement [Axis]
Total capital
Capitalization, Long-term Debt and Equity
2022 Approved Revenue Requirement [Member]
Two Thousand Twenty-Two Approved Revenue Requirement [Member]
Two Thousand Twenty-Two Approved Revenue Requirement [Member]
Fair Value Hierarchy and NAV [Domain]
Fair Value Hierarchy and NAV [Domain]
Debt and Credit Agreements
Debt Disclosure [Text Block]
Post-retirement and post-employment benefit liability (Note 20)
Postretirement And Postemployment Benefit Plans Liabilities Non Current
Postretirement and postemployment benefit plans liabilities non current.
Amendment Flag
Amendment Flag
Finite-Lived Intangible Assets, Major Class Name [Domain]
Finite-Lived Intangible Assets, Major Class Name [Domain]
Impact of tax deductions from deferred tax asset sharing
Effective Income Tax Rate Reconciliation, Tax Recovery From Deferred Tax Asset Sharing
Effective Income Tax Rate Reconciliation, Tax Recovery From Deferred Tax Asset Sharing
Aggregate number of common shares issuable under the plan (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized
Deferred income tax assets
Deferred Tax Assets, Gross [Abstract]
Interest on short-term notes
Interest Expense, Short-term Borrowings
Average service life, property, plant and equipment (in years)
Long Lived Assets And Intangible Assets Useful Life
Long Lived Assets And Intangible Assets Useful Life
Other Notes and Debentures [Member]
Other Notes And Debentures [Member]
Other Notes And Debentures [Member]
2037 [Member]
Two Thousand And Thirty Seven Expiry [Member]
Two Thousand And Thirty Seven Expiry [Member]
Amount reclassified
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax
Comprehensive income (loss) attributable to:
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Measurement Frequency [Axis]
Measurement Frequency [Axis]
Effect of a 1% increase in health care cost trends
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components
Outsourcing Services [Member]
Outsourcing Services [Member]
Outsourcing Services
Financial Instruments [Domain]
Financial Instruments [Domain]
Property Plant And Equipment Estimated Useful Lives [Table]
Property Plant And Equipment Estimated Useful Lives [Table]
Property Plant And Equipment Estimated Useful Lives [Table]
Expected return on plan assets, net of expenses
Defined Benefit Plan, Expected Return (Loss) on Plan Assets
Summary of Fair Value Hierarchy of Financial Assets and Liabilities
Fair Value, by Balance Sheet Grouping [Table Text Block]
Gain (loss) on derivative. net
Derivative, Gain (Loss) on Derivative, Net
Fair Value Measurement [Domain]
Fair Value Measurement [Domain]
Long-term debt issued
Proceeds from Issuance of Other Long-term Debt
Subsequent Events
Subsequent Events [Text Block]
Employee Share Ownership Plan (ESOP) [Member]
Employee Share Ownership Plan [Member]
Employee Share Ownership Plan [Member]
3.20% Series 25 Notes Due 2022 [Member]
Three Point Two Zero Percent Series Twenty Five Notes Due Two Thousand Twenty Two [Member]
Three Point Two Zero Percent Series Twenty Five Notes Due Two Thousand Twenty Two [Member]
Deferred income tax regulatory asset and liability
Deferred Tax Assets, Regulatory Assets and Liabilities
Reconciling items, property plant and equipment, total
Net Change In Accruals Included In Capital Investments
Net Change In Accruals Included In Capital Investments
Class B Units [Member]
Capital Unit, Class B [Member]
Operating lease renewal term (in years)
Lessee, Operating Lease, Renewal Term
Conservation and Demand Management (CDM) Variance [Member]
Conservation And Demand Management Variance [Member]
Conservation And Demand Management Variance
Allowance for doubtful accounts
Allowance for doubtful accounts – beginning
Allowance for doubtful accounts – ending
Provision for bad debts
Accounts Receivable, Allowance for Credit Loss, Current
Administration and Service [Member]
Administrative And Support Services And Others [Member]
Administrative And Support Services And Others [Member]
Income Statement Location [Domain]
Income Statement Location [Domain]
1.41% Series 2020-1 Notes Due 2027 [Member]
One Point Forty One Percent Series 2020-1 Notes Due Two Thousand Twenty Seven [Member]
One Point Forty One Percent Series 2020-1 Notes Due Two Thousand Twenty Seven
2022
2021
Lessee, Operating Lease, Liability, to be Paid, Year Two
Other Commitments [Line Items]
Other Commitments [Line Items]
Financing activities
Net Cash Provided by (Used in) Financing Activities [Abstract]
OEB fees
Related Party Reimbursement Expenses
Related party reimbursement expenses.
Depreciation, amortization and asset removal costs (Note 5)
Depreciation, amortization and asset removal costs
Utilities Operating Expense, Depreciation and Amortization
Foreign Exchange Contract [Member]
Foreign Exchange Contract [Member]
Schedule of Other Information Related to Operating Leases
Lease, Cost [Table Text Block]
Estimated annual pension plan contributions for 2026
Defined Benefit Plan, Expected Future Benefit Payment, Year Six
Defined Benefit Plan, Expected Future Benefit Payment, Year Six
2023
2022
Lessee, Operating Lease, Liability, to be Paid, Year Three
Other assets (Note 14)
Total other assets
Other Assets, Noncurrent
Plan Name [Axis]
Plan Name [Axis]
Long-term software/meter agreement, Year 2
Long Term Software and Meter Agreement Future Minimum Payments Due in Second Year
Amount of required minimum payments under Long term software and meter agreement due in second year.
Total liabilities
Financial Liabilities Fair Value Disclosure
Investment in subsidiaries
Deferred Tax Assets, Investment in Subsidiaries
Total assets
Total assets
Assets
Related Party Transactions
Related Party Transactions Disclosure [Text Block]
Interest earned on cash and cash equivalents
Interest Income, Deposits with Financial Institutions
Bonds and Debentures - Foreign [Member]
Debt Security, Government, Non-US [Member]
Interest Payments
Interest Expense, Debt
Units outstanding - beginning (in shares)
Units outstanding - ending (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number
3.91% Series 36 Notes Due 2046 [Member]
Three Point Nine One Percent Series Thirty Six Notes Due Two Thousand Forty Six [Member]
Three point nine one percent series thirty six notes due two thousand forty six.
Public Utilities, Regulatory Proceeding [Axis]
Public Utilities, Regulatory Proceeding [Axis]
Environmental Liabilities
Environmental Liabilities Disclosure [Text Block]
Environmental Liabilities Disclosure [Text Block]
Prior service cost amortization
Amortization of prior service cost
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)
Subsequent Event Type [Axis]
Subsequent Event Type [Axis]
Long-term debt measured at fair value
Fair Value Of Hedged Debt
Fair value of hedged debt.
Schedule of Common Stock Outstanding Roll Forward
Schedule of Common Stock Outstanding Roll Forward [Table Text Block]
Environmental Remediation Site [Domain]
Environmental Remediation Site [Domain]
Summary of Commitments Under Leases, Outsourcing and Other Agreements Due
Contractual Obligation, Fiscal Year Maturity [Table Text Block]
Other [Member]
Other Intangible Assets [Member]
Total liabilities
Liabilities
Depreciation and amortization in excess of capital cost allowance
Deferred Tax Assets Depreciation And Amortization
Deferred tax assets depreciation and amortization in excess of capital cost allowance.
Environmental liabilities (Note 21)
Accrued Environmental Loss Contingencies, Current
Fair value of shares granted
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Fair Value
Share-based compensation arrangement by share-based payment award options grants in period fair value.
Retirement Plan Type [Axis]
Retirement Plan Type [Axis]
Less: discounting minimum lease payments to present value
Lessee, Operating Lease, Liability, Undiscounted Excess Amount
ABO
Defined Benefit Plan, Accumulated Benefit Obligation
Employee contributions
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant
Schedule of Related Party Transactions, by Related Party [Table]
Schedule of Related Party Transactions, by Related Party [Table]
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Abstract]
Level 1 [Member]
Fair Value, Inputs, Level 1 [Member]
Sale of investments receivable excluded from fair value of pension plan assets
Sale Of Investments Receivable Excluded From Pension Plan Assets Fair Value
Sale of investments receivable excluded from pension plan assets fair value.
Summary of Number of DSUs
Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments [Table Text Block]
Regulated Operations [Abstract]
Regulated Operations [Abstract]
Avista Corporation [Member]
Avista Corporation [Member]
Avista Corporation [Member]
Asset Retirement Obligations [Table]
Asset Retirement Obligations [Table]
Asset Retirement Obligations [Table]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table]
Weighted-Average Interest Rate (as a percent)
Debt, Weighted Average Interest Rate
Defined Benefit Plan, Net Periodic Benefit, Type Of Cost (Credit) [Domain]
Defined Benefit Plan, Net Periodic Benefit, Type Of Cost (Credit) [Domain]
Defined Benefit Plan, Net Periodic Benefit, Type Of Cost (Credit)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of shares redeemed (in shares)
Stock Redeemed or Called During Period, Shares
Summary of Related Party Transactions
Related Party Transactions Details [Table Text Block]
Related party transactions details table.
Regulatory liabilities:
Regulatory Liabilities Abstract
Regulatory Liabilities Abstract
Contributions from sale of noncontrolling interest (Note 4)
Contributions from sale of noncontrolling interest, equity
Noncontrolling Interest, Increase from Sale of Parent Equity Interest
Additional Paid-in Capital [Member]
Additional Paid-in Capital [Member]
Preferred shareholder
Preferred shareholder
Preferred Stock Dividends and Other Adjustments
Assets:
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
2038 [Member]
Two Thousand And Thirty Eight Expiry [Member]
Two Thousand And Thirty Eight Expiry [Member]
Other
Other Operating Activities, Cash Flow Statement
Schedule of Effect of One Percent Change in Health Care Cost Trends on Projected Benefit Obligation
Schedule Of Effect Of One percent Change In Health Care Cost Trends On Projected Benefit Obligation [Table Text Block]
Schedule Of Effect Of One percent Change In Health Care Cost Trends On Projected Benefit Obligation
Granted (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted
Other long-term assets
Other Assets, Miscellaneous, Noncurrent
Actuarial loss
Defined Benefit Plan Future Amortization Of Actuarial Loss On Regulatory Assets
Amount included in regulatory assets related to actuarial loss expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.
Number of shares outstanding (in shares)
Common shares - beginning
Common shares - ending
Common Stock, Shares, Outstanding
Schedule of Other Current Assets
Schedule of Other Current Assets [Table Text Block]
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Abstract]
Revolving Credit Facility [Member]
Revolving Credit Facility [Member]
Other Current Assets
Other Current Assets [Text Block]
Schedule Of Weighted Average Assumption Determining Pension Plan And Other Post retirement Benefit Plan [Line Items]
Schedule Of Weighted Average Assumption Determining Pension Plan And Other Post retirement Benefit Plan [Line Items]
Schedule Of Weighted Average Assumption Determining Pension Plan And Other Post retirement Benefit Plan [Line Items]
Maximum term of hedges (in years)
Derivative, Term of Contract
Outstanding, beginning (in dollars per share)
Outstanding, ending (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price
Accounting Changes and Error Corrections [Abstract]
Accounting Changes and Error Corrections [Abstract]
Comprehensive Income / Loss
Comprehensive Income, Policy [Policy Text Block]
Percentage of common shares acquired
Business Acquisition, Percentage of Voting Interests Acquired
Effect of dilutive stock-based compensation plans (in shares)
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements
Property, Plant and Equipment
Property, Plant and Equipment, Gross
Entity Addresses, Address Type [Axis]
Entity Addresses, Address Type [Axis]
Estimated annual pension plan contributions for 2022
2022
Defined Benefit Plan, Expected Future Benefit Payment, Year Two
Short-term notes issued
Proceeds from Issuance of Commercial Paper
Summary of Segment Information
Schedule of Segment Reporting Information, by Segment [Table Text Block]
Unfunded status
Unfunded status
Defined Benefit Plan, Funded (Unfunded) Status of Plan
Hydro One Inc. [Member]
Hydro One Inc. [Member]
Hydro One Inc. [Member]
Net temporary differences attributable to regulated business
Effective Income Tax Rate Reconciliation, Deduction, Amount
Income Statement [Abstract]
Income Statement [Abstract]
Accumulated Other Comprehensive Loss [Member]
AOCI Attributable to Parent [Member]
6.6% Senior Secured Bonds due 2023 [Member]
Six Point Six Percent Senior Secured Bonds Due Two Thousand And Twenty Three [Member]
Six point six percent senior secured bonds due two thousand and twenty three.
Prepaid expenses and other assets
Increase (Decrease) in Prepaid Expense and Other Assets
Prior service cost for the year
Defined Benefit Plan, Prior Service Cost (Credit)
Defined Benefit Plan, Prior Service Cost (Credit)
Schedule of Segment Reporting Information, by Segment [Table]
Schedule of Segment Reporting Information, by Segment [Table]
Use of Management Estimates
Use of Estimates, Policy [Policy Text Block]
Deferred rebasing period (in years)
Deferred Rebasing Period
Deferred Rebasing Period
2022
Estimated Future Environmental Expenditures Due In Two Years
Estimated future environmental expenditures due in two year.
Dividends
Dividends
Long-term accounts payable
Due to Related Parties, Noncurrent
Schedule of Other Non-Current Assets
Schedule of Other Non-Current Assets [Table Text Block]
Schedule of Other Non-Current Assets [Table Text Block]
Intangible Assets
Intangible Assets [Policy Text Block]
Intangible Assets Policy [Text Block]
Capital Unit, Class [Domain]
Capital Unit, Class [Domain]
Rate of cost of living increase
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Cost Of Living Increase
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Cost Of Living Increase
Changes in Fair Value of Financial Instruments Classified in Level 3
Schedule of Changes in Fair Value of Plan Assets [Table Text Block]
Counterparty Name [Domain]
Counterparty Name [Domain]
Property, plant and equipment
Cash outflow for capital expenditures, property plant and equipment
Payments to Acquire Property, Plant, and Equipment
Hydro One Holdings Limited [Member]
Hydro One Holdings Limited [Member]
Hydro One Holdings Limited [Member]
Materials and Supplies
Materials And Supplies Policy [Policy Text Block]
Materials And Supplies Policy [Policy Text Block]
Due from related parties (Note 29)
Due from Related Parties, Current
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Abstract]
Type Of Benefit Obligation [Axis]
Type Of Benefit Obligation [Axis]
Type Of Benefit Obligation [Axis]
Net temporary differences recoverable in future rates charged to customers:
Net Temporary Differences [Abstract]
Net Temporary Differences [Abstract]
Additional equity interest available for purchase (as a percent)
Business Acquisition, Option To Purchase Additional Voting Interests Percentage
Business Acquisition, Option To Purchase Additional Voting Interests Percentage
Hydro One Sault Ste. Marie LP [Member]
Hydro One Sault Ste. Marie LP [Member]
Hydro One Sault Ste. Marie LP [Member]
Actual return on plan assets
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)
Accounts Receivable - Unbilled [Member]
Unbilled Revenues [Member]
Pension Plan Assets (as a percent)
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage
Other Long-Term Liabilities
Other Liabilities Disclosure [Text Block]
Hedging Designation [Axis]
Hedging Designation [Axis]
Other Services [Member]
Other Services [Member]
Other Services
Short-term debt
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities
2026 through to 2030
Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years
Interest and dividend receivable excluded from fair value of pension plan assets
Interest And Dividend Receivable Excluded From Pension Plan Assets Fair Value
Interest and dividend receivable excluded from pension plan assets fair value.
Transfer of pension assets
Transfer from other plans
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan
Entity [Domain]
Entity [Domain]
Easements [Member]
Land Easements [Member]
Land Easements [Member]
Designated as Hedging Instrument [Member]
Designated as Hedging Instrument [Member]
Forward exchange rate
Derivative, Forward Exchange Rate
2039 [Member]
Two Thousand And Thirty Nine Expiry [Member]
Two Thousand And Thirty Nine Expiry [Member]
Long-term debt repaid
Repayments of Medium-term Notes
Intangible Assets
Intangible Assets Disclosure [Text Block]
4.40% Series 20 Notes Due 2020 [Member]
Four Point Four Zero Percent Series Twenty Notes Due Two Thousand Twenty [Member]
Four Point Four Zero Percent Series Twenty Notes Due Two Thousand Twenty [Member]
Average service life, property, plant and equipment (in years)
Property, Plant and Equipment, Useful Life
Future environmental expenditure discount rate (as a percent)
Accrual for Environmental Loss Contingencies, Discount Rate
The Province [Member]
Affiliated Entity [Member]
Lessee, Lease, Description [Line Items]
Lessee, Lease, Description [Line Items]
Distribution Rate Riders [Member]
Distribution Rate Riders [Member]
Distribution Rate Riders [Member]
Post-Retirement and Post-Employment Benefits [Member]
Postretirement Benefit Costs [Member]
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Abstract]
Summary of Number of PSUs and RSUs
Schedule Of Performance Shares And Restricted Stock Units Activity [Table Text Block]
Schedule Of Performance Shares And Restricted Stock Units Activity
Effect of a 1% decrease in health care cost trends
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation
Net deferred income tax assets
Deferred Tax Assets, Net
Major Categories of Net Deferred Income Tax Assets
Net Deferred Income Tax Assets And Liabilities Table [Text Block]
Net deferred income tax assets and liabilities.
Committed amounts for leases that have not yet commenced
Lessee, Operating Lease, Lease Not Yet Commenced, Undiscounted Amount
Lessee, Operating Lease, Lease Not Yet Commenced, Undiscounted Amount
Share-based Payment Arrangement [Abstract]
Share-based Payment Arrangement [Abstract]
Land Assessment and Remediation [Member]
Land Assessment And Remediation [Member]
Land Assessment And Remediation [Member]
Maximum public offering amount
Maximum Public Offering Amount
Maximum Public Offering Amount
Lease obligations (Note 23)
Accounts payable and other current liabilities (Note 14)
Operating Lease, Liability, Current
Health care cost trend rate
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate
Outstanding, beginning (in shares)
Outstanding, ending (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number
Long-term debt payable within one year measured at fair value
Long-Term Debt, Current Maturities, Fair Value
Long-Term Debt, Current Maturities, Fair Value
Percentage of employer matching contribution
Employer matching contribution, percent of match
Defined Contribution Plan, Employer Matching Contribution, Percent of Match
Fair Value of Financial Instruments and Risk Management
Fair Value Disclosures [Text Block]
Regulatory assets (Note 13)
Regulatory assets
Regulatory Assets, Noncurrent
Increase (decrease) in amortization expense
Increase Decrease In Amortization Expense
Increase Decrease In Amortization Expense
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Rate Swap [Member]
Interest Rate Swap [Member]
Financing charges capitalized on property, plant and equipment
Allowance for Funds Used During Construction, Capitalized Interest
Employee Future Benefits
Pensions, Post-Retirement and Post Employment Benefits Policy [Policy Text Block]
Pensions, Post-Retirement and Post Employment Benefits Policy
Rate of increase in health care cost trends
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Health Care Cost Trend Rate
Defined benefit plan assumptions used calculating net periodic benefit cost health care cost trend rate.
Entity Registrant Name
Entity Registrant Name
Subsequent Event Type [Domain]
Subsequent Event Type [Domain]
Business Acquisition [Line Items]
Business Acquisition [Line Items]
Weighted-average discount rate (as a percent)
Operating Lease, Weighted Average Discount Rate, Percent
Directors' Deferred Share Units Plan [Member]
Directors' Deferred Share Units Plan [Member]
Directors' Deferred Share Units Plan [Member]
Asset impairment charges
Asset Impairment Charges
Interest on long-term debt
Interest Expense, Long-term Debt
Weighted-Average Price
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Less: current portion
Regulatory liabilities (Note 13)
Regulatory Liability, Current
Total regulatory assets
Regulatory assets
Regulatory Assets
Increase (decrease) in other comprehensive income
Increase Decrease In Other Comprehensive Income One
Increase (decrease) in other comprehensive income one attributable to regulated accounting.
Entity Incorporation, State or Country Code
Entity Incorporation, State or Country Code
Orillia Power Distribution Corporation [Member]
Orillia Power Distribution Corporation [Member]
Orillia Power Distribution Corporation.
Preferred share dividends
Dividends, Preferred Stock, Cash
Total depreciation and amortization
Depreciation, Depletion and Amortization, Nonproduction
Year 1 [Member]
Debt Instrument Maturity Period Year One [Member]
Debt Instrument Maturity Period Year One [Member]
Entity Address, Postal Zip Code
Entity Address, Postal Zip Code
Total deferred income tax assets
Deferred Tax Assets, Net of Valuation Allowance
Accounts Payable and Other Current Liabilities
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]
Derivative Instruments and Hedge Accounting
Derivatives, Methods of Accounting, Hedging Derivatives [Policy Text Block]
Undiscounted environmental liabilities
Environmental Liabilities Undiscounted Basis
Environmental liabilities undiscounted basis.
Regulatory liabilities
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Regulatory Liabilities
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Regulatory Liabilities
Goodwill (Note 4)
Total goodwill
Goodwill
2.54% Series 42 Notes Due 2024 [Member]
Two Point Five Four Percent Series Forty Two Notes Due Two Thousand Twenty Four [Member]
Two Point Five Four Percent Series Forty Two Notes Due Two Thousand Twenty Four [Member]
Thereafter [Member]
Debt Instrument Maturity Period Over Ten Years [Member]
Debt Instrument Maturity Period Over Ten Years [Member]
Payment on settlement
Payments for Hedge, Financing Activities
Dividends per common share declared (Note 22) (in dollars per share)
Dividends per common share declared (in dollars per share)
Common Stock, Dividends, Per Share, Declared
Long-term debt, face amount
Total
Long-term debt
Debt Instrument, Face Amount
Long-term software/meter agreement, Thereafter
Long Term Software and Meter Agreement Future Minimum Payments Due After Fifth Year
Amount of required minimum payments under Long term software and meter agreement due after fifth year.
Schedule of Long-Term Debt
Schedule Of Identified Noncurrent Liabilities [Table Text Block]
Schedule of identified noncurrent liabilities.
Other current assets (Note 10)
Other current assets
Other Assets, Current
Forfeited (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Total assets
Assets, Fair Value Disclosure
Equity
Equity [Abstract]
2024
Estimated Future Environmental Expenditures Due In Four Years
Estimated future environmental expenditures due in four year.
Schedule of Estimated Future Environmental Expenditures
Estimated Future Environmental Expenditures [Table Text Block]
Estimated Future Environmental Expenditures [Table Text Block]
Transmission [Member]
Electric Transmission [Member]
Pension Plans Postretirement And Other Employee Benefits [Table]
Pension Plans Postretirement And Other Employee Benefits [Table]
Pension Plans Postretirement And Other Employee Benefits [Table]
Diluted (in shares)
Weighted Average Number of Shares Outstanding, Diluted
Derivative Contract [Domain]
Derivative Contract [Domain]
Letters Of Credit [Member]
Letter of Credit [Member]
Schedule of Accounts Payable and Other Current Liabilities
Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]
Forfeited (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period
Debt Disclosure [Abstract]
Debt Disclosure [Abstract]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]
Operation, maintenance and administration (Notes 4, 29)
Operation, maintenance and administration
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses
Cash and Cash Equivalents [Member]
Defined Benefit Plan, Cash and Cash Equivalents [Member]
Unsecured Debt [Member]
Unsecured Debt [Member]
7.35% Debentures Due 2030 [Member]
Seven Point Thirty Five Percent Debentures Due Two Thousand Thirty [Member]
Seven Point Thirty Five Percent Debentures Due Two Thousand Thirty [Member]
Net cash from (used in) financing activities
Net Cash Provided by (Used in) Financing Activities
Year 5 [Member]
Debt Instrument Maturity Period Year Five [Member]
Debt Instrument Maturity Period Year Five [Member]
Prudential Support From IESO [Member]
Letters Of Credit, Prudential Support [Member]
Letters Of Credit, Prudential Support
Regulatory assets:
Regulatory Assets [Abstract]
Regulatory Assets [Abstract]
Counterparty Name [Axis]
Counterparty Name [Axis]
Estimated annual pension plan contributions for 2024
2024
Defined Benefit Plan, Expected Future Benefit Payment, Year Four
Defined Benefit Plan, Life Expectancy [Axis]
Defined Benefit Plan, Life Expectancy [Axis]
Defined Benefit Plan, Life Expectancy [Axis]
Other Regulatory Assets [Member]
Other Regulatory Assets [Member]
Other Regulatory Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets [Line Items]
Document Fiscal Year Focus
Document Fiscal Year Focus
Schedule Of Components Of Regulatory Assets Expected To Be Amortized As Components Of Net Periodic Benefit Cost [Line Items]
Schedule Of Components Of Regulatory Assets Expected To Be Amortized As Components Of Net Periodic Benefit Cost [Line Items]
Schedule Of Components Of Regulatory Assets Expected To Be Amortized As Components Of Net Periodic Benefit Cost [Line Items]
Deferred income tax assets
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets
Amortization expense for intangible assets, 2022
Finite-Lived Intangible Asset, Expected Amortization, Year Two
Other long-term assets:
Assets, Noncurrent [Abstract]
Long-term debt payable within one year (includes $303 measured at fair value; 2019 - $nil) (Notes 17, 18)
Long-term debt payable within one year
Long-term Debt, Current Maturities
Projected benefit obligation, beginning of year
Projected benefit obligation, end of year
PBO
Defined Benefit Plan, Benefit Obligation
Entity Current Reporting Status
Entity Current Reporting Status
Net Long-term debt payable within one year
Long Term Debt Current Net of Cash and Cash Equivalents
Long Term Debt Current Net of Cash and Cash Equivalents
Asset Removal Costs Cumulative Variance [Member]
Removal Costs [Member]
Related Party Transaction [Axis]
Related Party Transaction [Axis]
Outsourcing and other agreements, Year 2
Outsourcing Agreements Future Minimum Payments Due in Second Year
Amount of required minimum payments under outsourcing agreements due in second year.
Other Liabilities Disclosure [Abstract]
Other Liabilities Disclosure [Abstract]
Preferred shares redeemed (Note 24)
Value of shares redeemed
Stock Redeemed or Called During Period, Value
Comprehensive income
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest
Number of shares issued (in shares)
Common Stock, Shares, Issued
Recognition of deferred income tax regulatory asset (Note 13)
Effective Income Tax Rate Reconciliation, Recognition Of Deferred Income Tax Regulatory Asset
Effective Income Tax Rate Reconciliation, Recognition Of Deferred Income Tax Regulatory Asset
Cash and cash equivalents
Less: cash and cash equivalents
Cash and Cash Equivalents, at Carrying Value
OPG [Member]
Ontario Power Generation [Member]
Ontario Power Generation [Member]
Lowest percentage of participant's salary towards purchasing common shares
Share Based Compensation Arrangement By Share Based Payment Award Minimum Employee Subscription Rate
Share Based Compensation Arrangement By Share Based Payment Award Minimum Employee Subscription Rate
Total discounted minimum lease payments
Operating Lease, Liability
Long-term debt (includes $nil measured at fair value; 2019 - $351) (Notes 17, 18)
Long-term debt
Long-term Debt, Excluding Current Maturities
Segment Reporting [Abstract]
Segment Reporting [Abstract]
Debt Instrument [Line Items]
Debt Instrument [Line Items]
Hydro One shareholders’ equity
Stockholders' Equity Attributable to Parent
2.71% Series 47 Notes Due 2050 [Member]
Two Point Seven One Percent Series Forty Seven Notes Due Two Thousand Fifty [Member]
Two Point Seven One Percent Series Forty Seven Notes Due Two Thousand Fifty
Consideration transferred
Business Combination, Consideration Transferred
Entity Address, City or Town
Entity Address, City or Town
Fair Value Hierarchy and NAV [Axis]
Fair Value Hierarchy and NAV [Axis]
Intangible assets
Cash outflow for capital expenditures, intangible assets
Payments to Acquire Intangible Assets
Restricted Stock Units (RSUs) [Member]
Restricted Stock Units (RSUs) [Member]
Assumed health care cost trend, percentage
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year
Hydro One [Member]
Parent [Member]
Highest percentage of participant's salary towards purchasing common shares
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate
2025
2024
Lessee, Operating Lease, Liability, to be Paid, Year Five
Female [Member]
Female [Member]
Female [Member]
Financial Instrument [Axis]
Financial Instrument [Axis]
Post Retirement and Employment Benefits Regulatory Assets [Member]
Postretirement And Employment Benefits Regulatory Assets [Member]
Postretirement and employment benefits regulatory assets.
Capitalized Financing Costs
Interest Capitalization, Policy [Policy Text Block]
Fair value hedge exposure
Percentage Of Fair Value Hedge Exposure
Percentage Of Fair Value Hedge Exposure
Net income attributable to noncontrolling interest, equity
Noncontrolling Interest In Net Income Loss Equity
Amount of income (loss) attributable to noncontrolling Interest equity portion.
Medium Term Note Program [Member]
Medium Term Note Program [Member]
Medium Term Note Program [Member]
Stock-Based Compensation [Member]
Share Based Compensation [Member]
Share Based Compensation [Member]
Loss on pension and other post-employment benefits (OPEB) transfer (Note 20)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax
Dividends paid
Payments of Dividends
Less: valuation allowance
Valuation allowance in respect of capital property
Deferred Tax Assets, Valuation Allowance
Liabilities
Liabilities [Abstract]
Other long-term assets (Note 14)
Increase (Decrease) in Other Noncurrent Assets
Society Employee Share Ownership Plans [Member]
Society Employee Share Ownership Plans [Member]
Society Employee Share Ownership Plans [Member]
Capital units in initial investment
Capital Units, Net Amount
Amortization expense for intangible assets, 2023
Finite-Lived Intangible Asset, Expected Amortization, Year Three
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Business Contact
Business Contact [Member]
Revenue Recognition
Revenue from Contract with Customer [Policy Text Block]
Financing Charges
Interest Income and Interest Expense Disclosure [Text Block]
Capital Management
Capital Structure Disclosure [Text Block]
Capital Structure Disclosure [Text Block]
Other comprehensive loss (Note 8)
Other comprehensive loss
Other Comprehensive Income (Loss), Net of Tax
Regulatory Asset [Axis]
Regulatory Asset [Axis]
Leases [Abstract]
Leases [Abstract]
Other commitment, Year 4
Other Commitment, to be Paid, Year Four
Long-term Debt, Type [Axis]
Long-term Debt, Type [Axis]
Total current assets
Assets, Current
Other [Member]
Corporate and Other [Member]
2018 Approved Revenue Requirement [Member]
Two Thousand Eighteen Approved Revenue Requirement [Member]
Two Thousand Eighteen Approved Revenue Requirement [Member]
Noncontrolling interest (Note 28)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest
Earnings per common share (Note 26)
Earnings Per Share [Abstract]
Schedule of Deferred Income Tax Assets and Liabilities
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
Communication [Member]
Communications [Member]
Communications [Member]
Niagara Reinforcement Limited Partnership [Member]
Niagara Reinforcement Limited Partnership [Member]
Niagara Reinforcement Limited Partnership [Member]
Capital investment, property, plant and equipment
Capital Investments In Property Plant And Equipment
Capital Investments In Property Plant And Equipment
Long-term debt, market value
Long Term Debt Market Value
Fair value of debt instrument at date of acquisition less principal payments.
Amortization expense for intangible assets, 2025
Finite-Lived Intangible Asset, Expected Amortization, Year Five
2034 [Member]
Two thousand and Thirty four expiry [Member]
Two thousand and thirty four expiry.
Document Fiscal Period Focus
Document Fiscal Period Focus
Regulatory Assets and Liabilities
Schedule of Regulatory Assets and Liabilities [Text Block]
Discounted future expenditures (as a percent)
Asset Retirement Obligations Discounted Rate
Asset retirement obligations discounted rate.
Pension benefit liability (Note 20)
Pension benefit liability
Liability, Defined Benefit Pension Plan, Noncurrent
Annual pension plan contributions
Employer contributions
Defined Benefit Plan, Plan Assets, Contributions by Employer
Various Operating Purposes [Member]
Letters Of Credit, Various Operating Purposes [Member]
Letters Of Credit, Various Operating Purposes
Dividends
Dividend Disclosure [Text Block]
Dividend Disclosure [Text Block]
Society Share Grant Plan [Member]
Society Share Grant Plan [Member]
Society Share Grant Plan [Member]
Financing charges related to intangible assets under development
Financing Charges Related To Intangible Assets Under Development
Financing Charges Related To Intangible Assets Under Development
Environmental [Member]
Environmental [Member]
Environmental [Member]
Common Shares [Member]
Common Stock [Member]
Product and Service [Domain]
Product and Service [Domain]
Reconciling items, intangible assets
Net Change In Accruals Included In Capital Investments In Intangible Assets
Net Change In Accruals Included In Capital Investments In Intangible Assets
Accrued interest (Note 15)
Increase (Decrease) In Accrued Interest Payable
Increase (Decrease) In Accrued Interest Payable
Depreciation, Amortization And Asset Removal Costs
Depreciation And Amortization [Text Block]
Depreciation And Amortization [Text Block]
Other Commitments [Axis]
Other Commitments [Axis]
2.77% Series 35 Notes Due 2026 [Member]
Two Point Seven Seven Percent Series Thirty Five Notes Due Two Thousand Twenty Six [Member]
Two point seven seven percent series thirty five notes due two thousand twenty six.
6.35% Series 4 Notes Due 2034 [Member]
Six Point Three Five Percent Series Four Notes Due Two Thousand Thirty Four [Member]
Six Point Three Five Percent Series Four Notes Due Two Thousand Thirty Four [Member]
Due from related parties
Increase (Decrease) in Due from Related Parties, Current
Unusual or Infrequent Item, or Both [Domain]
Unusual or Infrequent Item, or Both [Domain]
Long-term debt, interest rate
Debt Instrument, Interest Rate, Stated Percentage
Liability recorded for potentially unsettled shares
Deferred Compensation Share-based Arrangements, Liability, Current
Derecognition of deferred financing costs (Note 4)
Derecognition of deferred financing costs (Note 4)
Write off of Deferred Debt Issuance Cost
Series 2 preferred shares [Member]
Series 2 Preferred Stock [Member]
Series 2 Preferred Stock
Schedule of Subsidiary of Limited Liability Company or Limited Partnership [Table]
Schedule of Subsidiary of Limited Liability Company or Limited Partnership [Table]
Number of shares exercised (in shares)
Exercised (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Net change in cash and cash equivalents
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect
Pension costs charged to regulatory assets
Pension Costs Charged To Regulatory Assets
Pension Costs Charged To Regulatory Assets
Total losses
Non capital losses carried forward to reduce future period taxable income
Non-capital losses carried forward to reduce future period taxable income.
Business Combinations
Business Combination Disclosure [Text Block]
Schedule of Accounts Receivable
Schedule Of Accounts Receivable Table [Table Text Block]
Schedule Of Accounts Receivable Table [Table Text Block]
Asset Retirement Obligations [Line Items]
Asset Retirement Obligations [Line Items]
Asset Retirement Obligations [Line Items]
Dividends on preferred shares
Dividends, Preferred Stock
Public Utility [Axis]
Public Utility [Axis]
Subsequent Events [Abstract]
Subsequent Events [Abstract]
Embedded derivatives
Embedded Derivative, Fair Value of Embedded Derivative, Net
COVID-19 Pandemic
COVID-19 Pandemic [Member]
COVID-19 Pandemic
Environmental Liabilities
Environmental Remediation Liabilities Policy [Policy Text Block]
Environmental Remediation Liabilities Policy [Policy Text Block]
Year 5
Long-Term Debt, Maturity, Year Five
Ownership [Domain]
Ownership [Domain]
Net interest paid
Interest Paid, Excluding Capitalized Interest, Operating Activities
2.16% Series 46 Notes Due 2030 [Member]
Two Point One Six Percent Series Forty Six Notes Due Two Thousand Thirty [Member]
Two Point One Six Percent Series Forty Six Notes Due Two Thousand Thirty
Working capital
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Working Capital
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Working Capital
Tax Period [Domain]
Tax Period [Domain]
Long-Term Debt Principal Repayments
Long-term Debt, Fiscal Year Maturity [Abstract]
Increase (decrease) to regulatory assets
Increase Decrease To Regulatory Assets
Increase (decrease) to regulatory assets.
Total equity
Beginning balance
Ending balance
Accumulated other comprehensive income (loss) related to cash flow hedges
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest
Additional paid-in capital (Note 27)
Additional Paid in Capital
Amortization expense for intangible assets, 2021
Finite-Lived Intangible Asset, Expected Amortization, Year One
Class of Stock [Axis]
Class of Stock [Axis]
Deferred Share Units [Member]
Deferred Share Unit [Member]
Deferred Share Unit [Member]
DSU value equivalent to common shares (in shares)
Share-based Compensation Arrangement By Share-based Payment Award, Non-Option Equity Based Instruments, Value Equivalent To Common Shares
Share-based Compensation Arrangement By Share-based Payment Award, Non-Option Equity Based Instruments, Value Equivalent To Common Shares
Components of Regulatory Assets That Have Not Been Recognized as Components of Net Periodic Benefit Costs
Components Of Regulatory Assets That Have Not Been Recognized As Components Of Net Periodic Benefit Costs [Table Text Block]
Components Of Regulatory Assets That Have Not Been Recognized As Components Of Net Periodic Benefit Costs Table [Text Block]
Accrued liabilities
Accrued Liabilities, Current
Diluted (in dollars per share)
Earnings Per Share, Diluted
Commitments [Table]
Commitments [Table]
Commitments [Table]
Contributions from sale of noncontrolling interest, temporary equity
Temporary Equity Contribution During Period Value
Temporary Equity Contribution During Period Value
Management Employee Share Ownership Plans [Member]
Management Employee Share Ownership Plans [Member]
Management Employee Share Ownership Plans [Member]
Business acquisition, consideration paid
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable
Schedule of Stock by Class [Table]
Schedule of Stock by Class [Table]
Noncontrolling Interest [Line Items]
Noncontrolling Interest [Line Items]
Year 4 [Member]
Debt Instrument Maturity Period Year Four [Member]
Debt Instrument Maturity Period Year Four [Member]
Schedule of Outstanding Long-Term Debt
Schedule of Long-term Debt Instruments [Table Text Block]
Depreciation of property, plant and equipment
Depreciation
Entity Address, Address Line One
Entity Address, Address Line One
Entity Address, Address Line Two
Entity Address, Address Line Two
Entity Emerging Growth Company
Entity Emerging Growth Company
Funding received related to CDM programs
Related party funding received for program costs, incentives and management fees
Related party funding received for program costs, incentives and management fees
Business combination percentage transferred
Business Combination Consideration Transferred Percentage
Business combination consideration transferred percentage.
Less: discounting environmental liabilities to present value
Accrued Discount Liability
Accrued discount liability.
Deferred income tax recovery
Deferred Income Tax Expense (Benefit)
Investments (Note 18)
Investments, Noncurrent
Investments, Noncurrent
Revenues related to provision of services and supply of electricity
Related Party Transaction, Other Revenues from Transactions with Related Party
Schedule of Changes in Fair Value of Financial Instruments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]
Utility Plant [Domain]
Utility Plant [Domain]
Transfer of pension obligations
Transfer from other plans
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) For Obligations Transferred To (From) Plan
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) For Obligations Transferred To (From) Plan
Annual Information Form
Annual Information Form
Paid (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised
Accumulated Amortization
Finite-Lived Intangible Assets, Accumulated Amortization
2020 Approved Revenue Requirement [Member]
Two Thousand Twenty Approved Revenue Requirement [Member]
Two Thousand Twenty Approved Revenue Requirement [Member]
Maximum [Member]
Maximum [Member]
Non-controlling Interest [Member]
Noncontrolling Interest [Member]
Contact Personnel Name
Contact Personnel Name
Realized and unrealized gains (losses)
Defined Benefit Plan Fair Value Of Plan Assets Realized And Unrealized Gains
Defined benefit plan fair value of plan assets realized and unrealized gains.
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments [Line Items]
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments [Line Items]
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments [Line Items]
Schedule of Financing Charges
Interest Income and Interest Expense Disclosure [Table Text Block]
Effective income tax rate
Effective Income Tax Rate Reconciliation, Percent
Net permanent differences
Net Permanent Differences Reconciliation
Net Permanent Differences Reconciliation
Electrical distribution, increased base rate
Electrical Distribution, Increased Base Rate
Electrical Distribution, Increased Base Rate
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Prior service cost
Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year
Accounts payable and other current liabilities (Note 15)
Total
Accounts Payable and Other Accrued Liabilities, Current
Post-Retirement and Post-Employment Benefits [Member]
Other Postretirement Benefits Plan [Member]
Weighted-average number of shares
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Defined Benefit Plan, Plan Liabilities, Category [Domain]
Defined Benefit Plan, Plan Liabilities, Category [Domain]
[Domain] for Defined Benefit Plan, Plan Liabilities, Category [Axis]
Regulatory Liability [Axis]
Regulatory Liability [Axis]
Schedule of Supplementary Balance Sheet Information
Assets And Liabilities, Lessee [Table Text Block]
Assets And Liabilities, Lessee [Table Text Block]
Schedule of Movements in Environmental Liabilities
Rollforward Of Environmental Liability [Table Text Block]
Rollforward Of Environmental Liability Table [Text Block]
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Segment Reporting Information [Line Items]
Segment Reporting Information [Line Items]
Fair Value, Recurring [Member]
Fair Value, Recurring [Member]
Foregone Revenue Deferral [Member]
Foregone Revenue Deferral [Member]
Foregone Revenue Deferral [Member]
Capital contributions received (Note 30)
Capital contribution received from OPG
Capital Contributions Received
Capital contributions received.
Share Grant Plans [Member]
Share Grant Plans [Member]
Share Grant Plans [Member]
Accrued dividends
Dividends, Preferred Stock, Stock
Document Type
Document Type
ICFR Auditor Attestation Flag
ICFR Auditor Attestation Flag
Shares granted (in shares)
Vested and issued (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross
Interest on convertible debentures (Note 4)
Interest Costs Incurred
Contributions from sale of noncontrolling interest
Minority Interest Temporary Equity And Equity Increase From Sales Of Noncontrolling Interest
Minority Interest Temporary Equity And Equity Increase From Sales Of Noncontrolling Interest
Payables and Accruals [Abstract]
Payables and Accruals [Abstract]
Additions
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Issues
Costs of Arranging Debt Financing
Accounting Policy For Costs Of Arranging Debt Financing Policy [Policy Text Block]
Accounting Policy For Costs Of Arranging Debt Financing Policy [Text Block]
Universal Base Shelf Prospectus [Member]
Universal Base Shelf Prospectus [Member]
Universal Base Shelf Prospectus
Segments [Axis]
Segments [Axis]
Regulatory assets and liabilities
Deferred Tax Liabilities Regulatory Amounts Receivable That Are Not Recognized For Tax Purposes
Deferred Tax Liabilities Regulatory Amounts Receivable That Are Not Recognized For Tax Purposes
3.79% Series 26 Notes Due 2062 [Member]
Three Point Seventy Nine Percent Series Twenty Six Notes Due Two Thousand Sixty Two [Member]
Three Point Seventy Nine Percent Series Twenty Six Notes Due Two Thousand Sixty Two [Member]
Schedule of Other Comprehensive Loss
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Noncontrolling interest
Noncontrolling Interest [Policy Text Block]
Noncontrolling Interest Policy [Text Block]
Level 3 [Member]
Fair Value, Inputs, Level 3 [Member]
Goodwill
Deferred Tax Liabilities, Goodwill
Retirement Compensation Arrangements [Member]
Letters Of Credit, Retirement Compensation Arrangements [Member]
Letters Of Credit, Retirement Compensation Arrangements
Leases
Lessee, Leases [Policy Text Block]
Long-term Purchase Commitment, Category of Item Purchased [Domain]
Long-term Purchase Commitment, Category of Item Purchased [Domain]
Costs related to the purchase of services
Related Party Transaction, Expenses from Transactions with Related Party
Benefits paid
Defined Benefit Plan, Plan Assets, Benefits Paid
Capital Expenditure [Abstract]
Capital Expenditure [Abstract]
Capital Expenditure
Defined Benefit Plan, Plan Liabilities, Category [Axis]
Defined Benefit Plan, Plan Liabilities, Category [Axis]
Defined Benefit Plan, Plan Liabilities, Category [Axis]
Deferred income tax liabilities (Note 7)
Deferred income tax liabilities
Deferred Income Tax Liabilities, Net
Maximum borrowing capacity
Commercial Paper Program Maximum Capacity
Maximum authorized borrowing capacity under the commercial paper program without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the commercial paper program.
Hydro One Limited [Member]
Hydro One Limited [Member]
Hydro One Limited [Member]
Intangible assets (Note 12)
Intangible Assets, Net (Excluding Goodwill)
Less: Interest capitalized on construction and development in progress
Interest Costs Capitalized Adjustment
4.17% Series 32 Notes Due 2044 [Member]
Four Point Seventeen Percent Series Thirty Two Notes Due Two Thousand Forty Four [Member]
Four Point Seventeen Percent Series Thirty Two Notes Due Two Thousand Forty Four [Member]
Forfeited (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value
Income before financing charges and income tax expense
Operating Income (Loss)
Life Expectancy At Age Sixty Five [Member]
Life Expectancy At Age Sixty Five [Member]
Life Expectancy At Age Sixty Five [Member]
Approximate life expectancy (in years) at particular age
Approximate Life Expectancy In years At Particular Age
Approximate life expectancy at particular age.
Noncontrolling Interest
Noncontrolling Interest Disclosure [Text Block]
Schedule of Allowance for Doubtful Accounts
Schedule Of Allowance For Doubtful Accounts [Table Text Block]
Tabular disclosure of the amount of bad debt provision charged against earnings and the amounts of accounts receivable written off.
Environmental liabilities (Note 21)
Accrued Environmental Loss Contingencies, Noncurrent
Post-retirement and post-employment benefits expense in excess of cash payments
Deferred Tax Assets Post Retirement And Post Employment Benefit Expense In Excess Of Cash Payments
Deferred Tax Assets Post Retirement And Post Employment Benefit Expense In Excess Of Cash Payments
Performance Share Units [Member]
Performance Share Units [Member]
Performance share units.
Six Nations of the Grand River Development Corporation [Member]
Six Nations Of The Grand River Development Corporation [Member]
Six Nations Of The Grand River Development Corporation [Member]
Schedule of Business Acquisitions, by Acquisition [Table]
Schedule of Business Acquisitions, by Acquisition [Table]
Contingencies and Commitments (Notes 31, 32)
Commitments and Contingencies
Vesting period (in years)
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period
Thereafter
Lessee, Operating Lease, Liability, to be Paid, after Year Five
Retail Settlement Variance Account [Member]
Retail Settlement Variance Accounts [Member]
Retail settlement variance accounts.
Incremental Bad Debt Expense [Member]
Incremental Bad Debt Expense [Member]
Incremental Bad Debt Expense
Distribution revenue requirement
Public Utilities, Approved Distribution Rates, Revenue Requirement
Public Utilities, Approved Distribution Rates, Revenue Requirement
Entity Address, State or Province
Entity Address, State or Province
Vested and issued (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period
Administrative expenses
Defined Benefit Plan, Plan Assets, Administration Expense
Accounts payable
Accounts Payable, Current
Income tax expense at statutory rate of 26.5% (2019 - 26.5%)
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount
Financial Asset, Period Past Due [Axis]
Financial Asset, Period Past Due [Axis]
Derivative assets (Note 18)
Derivative instruments
Derivative Asset, Current
Other Commitments [Table]
Other Commitments [Table]
Retained earnings
Retained Earnings (Accumulated Deficit)
Estimated annual pension plan contributions for 2027
Defined Benefit Plan, Expected Future Benefit Payment, Year Seven
Defined Benefit Plan, Expected Future Benefit Payment, Year Seven
Right-of-Use assets (Note 23)
Other long-term assets (Note 13)
Operating Lease, Right-of-Use Asset
Percentage of assets to ascertain concentration of credit risk
Percent of Assets to Phase in for Determining Risk Weighted Assets
Percentage of assets to ascertain concentration of credit risk.
2035 [Member]
Two thousand and thirty five expiry [Member]
Two thousand and thirty five expiry.
Amortization of regulatory assets
Amortization of Regulatory Asset
Discounted environmental liabilities
Environmental Liabilities Discounted Basis
Environmental liabilities discounted basis.
2036 [Member]
Two thousand and thirty six expiry [Member]
Two thousand and thirty six expiry.
Income taxes paid
Income Taxes Paid
Property, plant and equipment
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment
Pension plan average pensionable earnings (in years)
Defined Benefit Plan Average Pensionable Earnings
Defined benefit plan average pensionable earnings.
Administration and Service [Member]
Administrative Support Services [Member]
Administrative Support Services [Member]
Post-retirement and post-employment benefit liability
Increase (decrease) in post-retirement and post-employment benefit liability
Increase (decrease) in post-retirement and post-employment benefit liability
Summary of Principal Repayments and Related Weighted Average Interest Rates
Schedule of Maturities Principal and Interest of Long-term Debt [Table Text Block]
Tabular disclosure of the combined aggregate amount of maturities and weighted average interest rates for long-term borrowings.
6.93% Series 2 Notes Due 2032 [Member]
Six Point Nine Three Percent Series Two Notes Due Two Thousand Thirty Two [Member]
Six Point Nine Three Percent Series Two Notes Due Two Thousand Thirty Two [Member]
Public offering period (in months)
Public Offering Period
Public Offering Period
PCB [Member]
PCB [Member]
PCB [Member]
Income Taxes
Income Tax, Policy [Policy Text Block]
Hedging Designation [Domain]
Hedging Designation [Domain]
Long-term accounts payable and other long-term liabilities
Increase Decrease In Non Current Accounts Payable And Other Operating Liabilities
Increase decrease in non-current accounts payable and other operating liabilities.
Lease expense
Lease, Cost
Schedule of Other Long-Term Liabilities
Other Noncurrent Liabilities [Table Text Block]
Other
Interest Expense, Other
Other
Payments for (Proceeds from) Other Investing Activities
Weighted average expected rate of return on plan assets
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Return On Plan Assets
Defined benefit plan assumptions used calculating net periodic benefit cost rate of return on plan assets.
Payable to participants excluded from pension plan assets fair value
Payable To Participants Excluded From Pension Plan Assets Fair Value
Payable To Participants Excluded From Pension Plan Assets Fair Value
Hydro One Networks [Member]
Hydro One Networks [Member]
Hydro One Networks [Member]
Stock-based compensation (Note 27)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition
Asset retirement obligations (Note 22)
Asset retirement obligations recorded
Asset Retirement Obligation
Outsourcing and other agreements, Thereafter
Outsourcing Agreements Future Minimum Payments Due After Fifth Year
Amount of required minimum payments under outsourcing agreements due after fifth year.
Debt instrument maximum borrowing capacity
Debt Instrument, Maximum Borrowing Capacity
Debt Instrument, Maximum Borrowing Capacity
Construction in Progress
Construction in Progress, Gross
Revenues
Revenues
Revenue from Contract with Customer, Excluding Assessed Tax
Other commitment, Thereafter
Other Commitment, to be Paid, after Year Five
Schedule Of Effect Of One Percentage Point Change In Assumed Health Care Cost Trend Rates [Line Items]
Schedule Of Effect Of One Percentage Point Change In Assumed Health Care Cost Trend Rates [Line Items]
Schedule Of Effect Of One Percentage Point Change In Assumed Health Care Cost Trend Rates [Line Items]
Closing share price of common shares (in dollars per share)
Share Price
Pension costs capitalized
Pension Costs Capitalized
Pension costs capitalized.
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Regulatory Liability [Domain]
Regulatory Liability [Domain]
Business Acquisition [Axis]
Business Acquisition [Axis]
Net income
Net Income Loss Net Of Adjustments To Noncontrolling Interest Subject To Redemption
Net income loss net of adjustments to noncontrolling interest subject to redemption.
Non Capital Losses Carried Forward to Reduce Future Period Taxable Income
Non Capital Losses Carried Forward By Year Of Expiry [Table Text Block]
Non capital losses carried forward by year of expiry.
Schedule Of Weighted Average Assumptions Determining Pension Plan And Other Post retirement Benefit Plan [Table]
Schedule Of Weighted Average Assumptions Determining Pension Plan And Other Post retirement Benefit Plan [Table]
Schedule Of Weighted Average Assumptions Determining Pension Plan And Other Post retirement Benefit Plan [Table]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Disclosure [Line Items]
Pooled Funds [Member]
Fixed Income Funds [Member]
5.36% Series 9 Notes Due 2036 [Member]
Five Point Thirty Six Percent Series Nine Notes Due Two Thousand Thirty Six [Member]
Five Point Thirty Six Percent Series Nine Notes Due Two Thousand Thirty Six [Member]
1.84% Series 34 Notes Due 2021 [Member]
One Point Eight Four Percent Series Thirty Four Notes Due Two Thousand Twenty One [Member]
One point eight four percent series thirty four notes due two thousand twenty one.
Deferred income tax recovery
Increase (Decrease) in Deferred Income Taxes
Accrued interest
Interest Payable, Current
2019 Approved Revenue Requirement [Member]
Two Thousand Nineteen Approved Revenue Requirement [Member]
Two Thousand Nineteen Approved Revenue Requirement [Member]
Credit Facility [Axis]
Credit Facility [Axis]
Preferred shares issued (in shares)
Preferred Stock, Shares Issued
Derivative liabilities (Note 18)
Derivative Liability, Noncurrent
Amortization of actuarial losses
Defined Benefit Plan Actuarial Loss Amortization
Defined benefit plan actuarial loss amortization.
Increase (decrease) to operation, maintenance, administration and depreciation expenses
Increase Decrease To Operation Maintenance Administration And Depreciation Expense
Increase (decrease) to operation maintenance administration and depreciation expense.
Business Combinations [Abstract]
Business Combinations [Abstract]
Retirement Plan Name [Domain]
Retirement Plan Name [Domain]
Net income from acquiree
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Disclosure [Abstract]
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Annual rate of depreciation and amortization, property, plant and equipment
Annual Depreciation and Amortization Rate Range
Annual Depreciation and Amortization Rate Range
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distributions to noncontrolling interest, temporary equity
Temporary Equity Distribution During Period Value
Temporary Equity Distribution During Period Value
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments [Table]
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments [Table]
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments [Table]
Common shares issued (Note 24)
Value of common shares issued
Proceeds from Issuance of Common Stock
Financial Asset, Period Past Due [Domain]
Financial Asset, Period Past Due [Domain]
Schedule of Earnings Per Share, Basic and Diluted
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Commitments
Commitments Disclosure [Text Block]
Schedule of Movements in Noncontrolling Interest
Summary Of Noncontrolling Interest [Table Text Block]
Summary Of Noncontrolling Interest
Payments made
Loss Contingency Accrual, Payments
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]
Amount Drawn
Long-term Line of Credit
Loan repaid and redeemed
Repayments of Debt
Defined Benefit Plan, Plan Assets, Category [Axis]
Defined Benefit Plan, Plan Assets, Category [Axis]
Net cash from operating activities
Net Cash Provided by (Used in) Operating Activities
Billing Status, Type [Axis]
Billing Status, Type [Axis]
Entity Central Index Key
Entity Central Index Key
Debt Premium [Member]
Debt Premium [Member]
Debt Premium [Member]
Related Party [Domain]
Related Party [Domain]
Computer Applications Software [Member]
Computer Software, Intangible Asset [Member]
Related Party Transaction [Line Items]
Related Party Transaction [Line Items]
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Derivative Instrument [Axis]
Derivative Instrument [Axis]
Schedule of Regulatory Assets and Liabilities
Schedule Of Regulatory Assets And Liabilities [Table Text Block]
Schedule Of Regulatory Assets And Liabilities [Table Text Block]
Finite-Lived Intangible Assets by Major Class [Axis]
Finite-Lived Intangible Assets by Major Class [Axis]
Schedule of Intangible Assets
Schedule of Finite-Lived Intangible Assets [Table Text Block]
Consolidated Statements of Cash Flows
Cash Flow, Supplemental Disclosures [Text Block]
Total fair value of plan liabilities
Liability, Defined Benefit Plan
Deferred Income Tax Assets And Liabilities [Line Items]
Deferred Income Tax Assets And Liabilities [Line Items]
Deferred Income Tax Assets And Liabilities [Line Items]
Entity Primary SIC Number
Entity Primary SIC Number
Grant date total fair value of awards
Share Based Compensation Arrangement By Share Based Payment Award Equity Instrument Other Than Options Grants In Period Fair Value
Share Based Compensation Arrangement By Share Based Payment Award Equity Instrument Other Than Options Grants In Period Fair Value
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrual for Environmental Loss Contingencies [Roll Forward]
Increase (decrease) in operation, maintenance and administration expenses
Increase Decrease To Selling, General And Administrative Expenses
Increase (decrease) to selling, general and administrative expenses attributable to regulatory accounting.
Interest accretion
Interest Accretion
Interest accretion.
Post-retirement and post-employment benefit liability
Liability, Other Postretirement Defined Benefit Plan, Noncurrent
Segments [Domain]
Segments [Domain]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Statement of Cash Flows [Abstract]
Statement of Cash Flows [Abstract]
Year 3 [Member]
Debt Instrument Maturity Period Year Three [Member]
Debt Instrument Maturity Period Year Three [Member]
Year 4
Long-Term Debt, Maturity, Year Four
Settled (in shares)
Settled (in shares)
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Settled In Period
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Settled In Period
Schedule of Credit Facilities
Schedule of Line of Credit Facilities [Table Text Block]
Province Of Ontario [Member]
Majority Shareholder [Member]
Asset removal costs
Amortization Of Capitalized Asset Retirement Obligation Costs
The amortization of the asset retirement obligation costs that got capitalized.
Income Statement Location [Axis]
Income Statement Location [Axis]
Guarantees [Member]
Guarantees [Member]
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
Thereafter
Estimated Future Environmental Expenditures Due Thereafter
Estimated future environmental expenditures due thereafter.
Annual average rate of amortization, intangible assets
Average Amortization Rate On Intangible Assets
Average amortization rate on intangible assets.
2025
Estimated Future Environmental Expenditures Due In Five Years
Estimated future environmental expenditures due in five year.
Notional value
Derivative, Notional Amount
Amortization of intangible assets
Amortization of Intangible Assets
Line of Credit Facility [Table]
Line of Credit Facility [Table]
Payments for interest
Payments For Interest
Payments For Interest
2021
Estimated Future Environmental Expenditures Due In One Year
Estimated future environmental expenditures due in one year.
Basis of Consolidation and Presentation
Basis Of Consolidation [Policy Text Block]
Basis Of Consolidation Policy [Text Block]
Capital Investments
Capital investments
Capital Investments
Capital Investments
4.89% Series 12 Notes Due 2037 [Member]
Four Point Eighty Nine Percent Series Twelve Notes Due Two Thousand Thirty Seven [Member]
Four Point Eighty Nine Percent Series Twelve Notes Due Two Thousand Thirty Seven [Member]
Segmented Reporting
Segment Reporting Disclosure [Text Block]
Common shares issued
Stock Issued During Period, Value, New Issues
Add: Unrealized mark-to-market loss (gain)
Unrealized Mark To Market Loss Gain
Unrealized mark to market loss gain.
Option Three [Member]
Option Three [Member]
Option Three [Member]
Derivative liabilities (Note 18)
Derivative Liability, Current
Pension obligations
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions
Title of 12(b) Security
Title of 12(b) Security
Total
Finite-Lived Intangible Assets, Net
Weighted-average exercise price, granted (in dollars per share)
Vested and issued (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value
Other assets
Assets for Plan Benefits, Defined Benefit Plan
Description of the Business
Business Description and Basis of Presentation [Text Block]
Depreciation and amortization (Note 5)
Depreciation and amortization
Depreciation, Depletion and Amortization
4.39% Series 23 Notes Due 2041 [Member]
Four Point Thirty Nine Percent Series Twenty Three Notes Due Two Thousand Forty One [Member]
Four Point Thirty Nine Percent Series Twenty Three Notes Due Two Thousand Forty One [Member]
Major Components of Income Tax Expense
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
Ownership percentage
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners
Schedule of Accounting Standards Updates Issued by Financial Accounting Standards Board
Accounting Standards Update and Change in Accounting Principle [Table Text Block]
Environmental Remediation Site [Axis]
Environmental Remediation Site [Axis]
Product and Service [Axis]
Product and Service [Axis]
Financial Assets and Liabilities
Fair Value Of Financial Assets And Liabilities [Policy Text Block]
Disclosure of accounting policy for fair value of financial assets and liabilities.
Thereafter
Long Term Debt, Maturities, Repayments of Principal in Over Ten Years
Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in over the tenth fiscal year following the latest fiscal year.
Regulatory Assets [Member]
Regulatory Assets [Member]
Regulatory assets.
5.49% Series 18 Notes Due 2040 [Member]
Five Point Forty Nine Percent Series Eighteen Notes Due Two Thousand Forty [Member]
Five Point Forty Nine Percent Series Eighteen Notes Due Two Thousand Forty [Member]
Other commitment, Year 5
Other Commitment, to be Paid, Year Five
Year 2
Long-Term Debt, Maturity, Year Two
Common shareholder
Net income (loss) attributable to common shareholders
Net Income (Loss) Available to Common Stockholders, Basic
Accounts payable
Increase (Decrease) in Accounts Payable
Unrealized loss on Foreign-Exchange Contract (Note 4)
Financing charges
Unrealized gains reversed in financing charges
Unrealized Gain (Loss) on Derivatives
6.59% Series 5 Notes Due 2043 [Member]
Six Point Fifty Nine Percent Series Five Notes Due Two Thousand Forty Three [Member]
Six Point Fifty Nine Percent Series Five Notes Due Two Thousand Forty Three [Member]
Long-term inflation rate assumption of current costs (as a percent)
Long-term inflation assumption of current costs (as a percent)
Inflation Rate
Inflation rate.
Deferred Income Tax Regulatory Liability [Member]
Deferred Income Tax Regulatory Liability[Member]
Deferred Income Tax Regulatory Liability[Member]
Debt Instrument [Axis]
Debt Instrument [Axis]
Asset Retirement Obligations
Asset Retirement Obligation Disclosure [Text Block]
Fair Value Hedging [Member]
Fair Value Hedging [Member]
Amounts Related To Electricity Rebates [Member]
Amounts Related To Electricity Rebates [Member]
Amounts Related To Electricity Rebates [Member]
Accrued liabilities
Increase (Decrease) in Accrued Liabilities
Class of Stock [Line Items]
Class of Stock [Line Items]
Changes in non-cash balances related to operations (Note 30)
Changes in non-cash balances related to operations, Total
Increase (Decrease) in Operating Capital
Derivative instruments
Derivative Liability
Adjustments for non-cash items:
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Accounts receivable, gross
Accounts Receivable, before Allowance for Credit Loss, Current
Schedule Of Regulatory Assets And Liabilities [Line Items]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Additions to allowance for doubtful accounts
Additions to allowance for doubtful accounts related to the COVID-19 pandemic
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)
Preferred stock redeemed and accrued dividends
Stock Redeemed Or Called During Period, Preferred Stock And Accrued Dividends, Value
Stock Redeemed Or Called During Period, Preferred Stock And Accrued Dividends, Value
Number of shares modified (in shares)
Share Issued, Number Of Shares Modified
Share Issued, Number Of Shares Modified
Reconciliation between Undiscounted Basis of Environmental Liabilities and Amount Recognized on Consolidated Balance Sheets
Reconciliation Between Undiscounted Basis And Amount Recognized In Consolidated Balance Sheets Factoring Discount Rate [Table Text Block]
Reconciliation Between Undiscounted Basis And Amount Recognized In Consolidated Balance Sheets Factoring Discount Rate [Table Text Block]
Environmental expenditures
Deferred Tax Assets Environmental Reserve
Deferred Tax Assets Environmental Reserve
Funded percentage
Defined Benefit Plan, Funded Percentage
Net income attributable to noncontrolling interest, temporary equity
Temporary Equity, Net Income
Subsequent Event [Member]
Subsequent Event [Member]
Accruals for pension administration expense excluded from fair value of pension plan assets
Accruals For Pension Administration Expense And Foreign Exchange Contracts Payable Excluded From Pension Plan Assets Fair Value
Accruals for pension administration expense and foreign exchange contracts payable excluded from pension plan assets fair value.
Distribution [Member]
Electric Distribution [Member]
Cash as part of the transfer
Defined Benefit Plan, Plan Assets, Increase (Decrease) For Assets Transferred To (From) Plan, Cash
Defined Benefit Plan, Plan Assets, Increase (Decrease) For Assets Transferred To (From) Plan, Cash
Post-Retirement and Post-Employment Benefits Non-Service Cost [Member]
Pension And Other Postretirement Plans Non-service Cost [Member]
Pension And Other Postretirement Plans Non-service Cost [Member]
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]
Saugeen Ojibway Nation (SON) [Member]
Saugeen Ojibway Nation [Member]
Saugeen Ojibway Nation [Member]
Regulatory assets and liabilities
Regulatory Assets And Liabilities, Non-Cash Adjustment
Regulatory Assets And Liabilities, Non-Cash Adjustment
1.62% Series 33 Notes Due 2020 [Member]
One Point Six Two Percent Thirty Three Notes Due Two Thousand Twenty [Member]
One Point Six Two Percent Thirty Three Notes Due Two Thousand Twenty [Member]
Tax Rule Changes Variance [Member]
Tax Rule Changes Variance [Member]
Tax Rule Changes Variance [Member]
Schedule of Pension Plan Target Asset and Weighted Average Asset Allocations
Schedule Of Pension Plan Target Asset And Weighted Average Asset Allocations [Table Text Block]
Schedule Of Pension Plan Target Asset And Weighted Average Asset Allocations
Fair Value [Member]
Estimate of Fair Value Measurement [Member]
Requisite service period (in years)
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period
Banking and Thrift, Interest [Abstract]
Banking and Thrift, Interest [Abstract]
Lease obligations (Note 23)
Other long-term liabilities (Note 15)
Operating Lease, Liability, Noncurrent
Amortization expense for intangible assets, 2024
Finite-Lived Intangible Asset, Expected Amortization, Year Four
Depreciation and Amortization
Depreciation, Depletion, and Amortization [Policy Text Block]
Current assets:
Assets, Current [Abstract]
Green Energy Expenditure Variance [Member]
Green Energy expenditure variance [Member]
Green Energy expenditure variance [Member]
OCN LP [Member]
OCN LP [Member]
OCN LP [Member]
Purchases
Defined Benefit Plan Fair Value Of Plan Assets Purchases
Defined benefit plan fair value of plan assets purchases.
Investments (Note 14)
Investments, Fair Value Disclosure
Property Plant And Equipment Estimated Useful Lives [Line Items]
Property Plant And Equipment Estimated Useful Lives [Line Items]
Property Plant And Equipment Estimated Useful Lives [Line Items]
Earnings Sharing Mechanism Deferral [Member]
Earnings Sharing Mechanism Deferral [Member]
Earnings Sharing Mechanism Deferral [Member]
Common shareholder
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Purchase of investments payable excluded from fair value of pension plan assets
Purchase Of Investments Payable Excluded From Pension Plan Assets Fair Value
Purchase of investments payable excluded from pension plan assets fair value.
4.6% Note Payable due 2023 [Member]
Four Point Six Percent Notes Payable Due Two Thousand And Twenty Three [Member]
Four point six percent notes payable due two thousand and twenty three.
Year 1
Long-Term Debt, Maturity, Year One
Reconciliation between Statutory and Effective Tax Rates
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Rate of compensation scale escalation (long-term)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase
Legal Entity [Axis]
Legal Entity [Axis]
City Area Code
City Area Code
Account receivable, period (in days)
Accounts Receivable Collection Period
Accounts Receivable Collection Period
Schedule of Projected Benefit Obligation (PBO), Accumulated Benefit Obligation (ABO) and Fair Value of Plan Assets
Schedule of Accumulated and Projected Benefit Obligations [Table Text Block]
Non-capital losses
Deferred Tax Assets Non Capital Losses
Deferred tax assets non capital losses.
Document Period End Date
Document Period End Date
Average Service Lives and Depreciation and Amortization Rates
Depreciation Depletion And Amortization Methods And Rates Of Property Plant And Equipment [Table Text Block]
Depreciation Depletion And Amortization Methods And Rates Of Property Plant And Equipment
Redemption price (in cad per share)
Preferred Stock, Redemption Price Per Share
Schedule Of Effect Of One Percentage Point Change In Assumed Health Care Cost Trend Rates [Table]
Schedule Of Effect Of One Percentage Point Change In Assumed Health Care Cost Trend Rates [Table]
Schedule Of Effect Of One Percentage Point Change In Assumed Health Care Cost Trend Rates [Table]
Defined Benefit Plan, Labor [Member]
Defined Benefit Plan, Labor [Member]
Defined Benefit Plan, Labor
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]
Net income
Net income (loss)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest
Pension Cost Differential [Member]
Pension Cost Variance [Member]
Pension Cost Variance [Member]
Operating lease term (in years)
Lessee, Operating Lease, Term of Contract
Debt [Member]
Debt [Member]
Audited Annual Financial Statements
Audited Annual Financial Statements
Option Two [Member]
Option Two [Member]
Option Two [Member]
Deferred Income Tax Regulatory Asset [Member]
Deferred Income Tax Charge [Member]
Environmental expenditures
Payments for Environmental Liabilities
Long-term Debt, Type [Domain]
Long-term Debt, Type [Domain]
Cash outflow for capital expenditures, total
Payments to Acquire Productive Assets
Increase (decrease) in revenue
Increase Decrease In Revenue
Increase (decrease) in revenue attributable to regulatory accounting.
Years 6-10
Long Term Debt, Maturities, Repayments of Principal Between Six to Ten Year
Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing between sixth to tenth fiscal year following the latest fiscal year.
6.03% Series 17 Notes Due 2039 [Member]
Six Point Zero Three Percent Series Seventeen Notes Due Two Thousand Thirty Nine [Member]
Six Point Zero Three Percent Series Seventeen Notes Due Two Thousand Thirty Nine [Member]
Costs to obtain financing
Proceeds from (Payments for) Other Financing Activities
Cover [Abstract]
Agreement term (in years)
Long-term Purchase Commitment, Period
4.59% Series 29 Notes Due 2043 [Member]
Four Point Five Nine Percent Series Twenty Nine Notes Due Two Thousand Forty Three [Member]
Four Point Five Nine Percent Series Twenty Nine Notes Due Two Thousand Forty Three [Member]
Regulatory Asset [Domain]
Regulatory Asset [Domain]
Realized loss on cash flow hedges (interest-rate swap agreements) (Note 8, 18)
Derivative, Loss on Derivative
Non-depreciable capital property
Deferred Tax Assets Non Depreciable Capital Property
Deferred tax assets non depreciable capital property.
Debt Service Reserve Requirements [Member]
Letters Of Credit, Debt Service Reserve Requirements [Member]
Letters Of Credit, Debt Service Reserve Requirements
Carrying Value
Total long-term debt
Long-term Debt
Leases
Lessee, Operating Leases [Text Block]
Taxes payable excluded from pension plan assets fair value
Taxes Payable Excluded From Pension Plan Assets Fair Value
Taxes Payable Excluded From Pension Plan Assets Fair Value
Employee contributions
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant
Retirement Plan Name [Axis]
Retirement Plan Name [Axis]
Effect of a 1% decrease in health care cost trends
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components
Current service cost
Defined Benefit Plan, Service Cost
Total
Estimated Future Environmental Expenditures Due
Estimated future environmental expenditures due.
Medium-term Notes [Member]
Medium-term Notes [Member]
Purchased power (includes $2,513 related party costs; 2019 - $1,818) (Note 29)
Purchased power
Cost of Goods and Services Sold
4.00% Series 24 Notes Due 2051 [Member]
Four Point Zero Zero Percent Series Twenty Four Notes Due Two Thousand Fifty One [Member]
Four Point Zero Zero Percent Series Twenty Four Notes Due Two Thousand Fifty One [Member]
Total costs
Costs and Expenses
Type Of Benefit Obligation [Domain]
Type Of Benefit Obligation [Domain]
[Domain] for Type Of Benefit Obligation [Axis]
Equity Components [Axis]
Equity Components [Axis]
Regulatory Matters [Line Items]
Regulatory Matters [Line Items]
Regulatory Matters [Line Items]
Asset Retirement Obligations
Asset Retirement Obligation [Policy Text Block]
Environmental expenditures
Environmental Expenditures Reconciliation
Environmental Expenditures Reconciliation
Debt Instrument, Name [Domain]
Debt Instrument, Name [Domain]
Receivables [Abstract]
Receivables [Abstract]
Deferred income tax assets gross
Deferred Tax Assets, Gross
Minimum [Member]
Minimum [Member]
Capital investments, intangible assets
Capital Investments In Intangible Assets
Capital Investments In Intangible Assets
Schedule of Consolidated Statement of Cash Flows
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]
Defined Benefit Plan, Plan Assets, Category [Domain]
Defined Benefit Plan, Plan Assets, Category [Domain]
Equity Securities [Member]
Defined Benefit Plan, Equity Securities [Member]
Components of Regulatory Assets Expected to be Amortized as Components of Net Periodic Benefit Costs
Components Of Regulatory Assets To Be Amortized Net Periodic Benefit Costs [Table Text Block]
Components Of Regulatory Assets To Be Amortized Net Periodic Benefit Costs Table [Text Block]
Fair Value Of Financial Instruments [Line Items]
Fair Value Of Financial Instruments [Line Items]
Fair Value Of Financial Instruments [Line Items]
Noncontrolling interest (Note 28)
Net income attributable to noncontrolling interest
Net Income (Loss) Attributable to Noncontrolling Interest
Long-term:
Non Current Deferred Income Taxes [Abstract]
Non current deferred income taxes.
Trilliant Agreement [Member]
Trilliant Agreement [Member]
Trilliant agreement.
Amortization of actuarial losses
Defined Benefit Plan, Amortization of Gain (Loss)
Entity Interactive Data Current
Entity Interactive Data Current
Net periodic benefit costs
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Exercised (in dollars per share)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price
Pension Plan Assets Measured and Recorded at Fair Value on Recurring Basis
Schedule of Allocation of Plan Assets [Table Text Block]
Revenues
Revenues [Abstract]
Operating activities
Net Cash Provided by (Used in) Operating Activities [Abstract]
Share Capital
Stockholders' Equity Note Disclosure [Text Block]
Employee Stock Ownership Plan (ESOP), Plan [Domain]
Employee Stock Ownership Plan (ESOP), Plan [Domain]
Summary of Share Grant Activity
Share-based Payment Arrangement, Option, Activity [Table Text Block]
5 Years, Total [Member]
Debt Instrument Maturity Period At End of Fifth Year [Member]
Debt Instrument Maturity Period At End of Fifth Year [Member]
Accounts Receivable - Billed [Member]
Billed Revenues [Member]
Stock-Based Compensation
Share-based Payment Arrangement [Policy Text Block]
During 5 years
Long Term Debt Maturities Aggregate Repayments Of Principal Next Five Years
Long Term Debt Maturities Aggregate Repayments Of Principal Next Five Years
Unusual or Infrequent Item, or Both [Axis]
Unusual or Infrequent Item, or Both [Axis]
Fair Value Of Financial Instruments [Table]
Fair Value Of Financial Instruments [Table]
Fair Value Of Financial Instruments [Table]
Statement of Stockholders' Equity [Abstract]
Statement of Stockholders' Equity [Abstract]
Real Estate and Infrastructure [Member]
Defined Benefit Plan, Real Estate [Member]
2021
Defined Benefit Plan, Expected Future Benefit Payment, Year One
Defined Benefit Plan, Life Expectancy [Domain]
Defined Benefit Plan, Life Expectancy [Domain]
[Domain] for Defined Benefit Plan, Life Expectancy [Axis]
Total deferred income tax liabilities
Deferred Tax Liabilities, Gross
Disposition period (in years)
Disposition Period
Disposition Period
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
DSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Fixed-to-floating interest-rate swap, term (in years)
Fixed To Floating Interest Rate Swaps, Term
Fixed To Floating Interest Rate Swaps, Term
Number of reportable segments
Number of Reportable Segments
Environmental Remediation Obligations [Abstract]
Environmental Remediation Obligations [Abstract]
Retirement Plan Type [Domain]
Retirement Plan Type [Domain]
Reclassified within next twelve months
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months
Forward Agreements [Member]
Forward Contracts [Member]
Charged to results of operations [Member]
Utilities Operating Expense, Maintenance, Operations, And Other Costs And Expenses [Member]
Utilities Operating Expense, Maintenance, Operations, And Other Costs And Expenses
Number of plans
Number Of Plans
Number Of Plans
Environmental Liabilities [Table]
Environmental Liabilities [Table]
Environmental Liabilities [Table]
Accounts receivable (Note 9)
Accounts receivable, net
Accounts Receivable, after Allowance for Credit Loss, Current
Total undiscounted minimum lease payments
Lessee, Operating Lease, Liability, to be Paid
Ownership interest in related party (as a percent)
Noncontrolling Interest, Ownership Percentage by Parent
Preferred Shares [Member]
Series 1 Preferred Stock [Member]
Series 1 Preferred Stock
Other
Deferred Tax Assets, Other
Noncontrolling Interest [Abstract]
Noncontrolling Interest [Abstract]
Other commitment, Year 2
Other Commitment, to be Paid, Year Two
Fair value of assets - beginning
Fair value of assets - ending
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs
Title of Individual [Axis]
Title of Individual [Axis]
Other long-term liabilities
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other
3.63% Series 41 Notes Due 2049 [Member]
Three Point Six Three Percent Series Forty One Notes Due Two Thousand Forty Nine [Member]
Three Point Six Three Percent Series Forty One Notes Due Two Thousand Forty Nine [Member]
2040 [Member]
Two Thousand And Forty Expiry [Member]
Two Thousand And Forty Expiry
Annual rate of amortization, intangible assets
Amortization Rate on Intangible Assets
Amortization Rate on Intangible Assets
Credit Facilities [Member]
Credit Facilities [Member]
Credit Facilities [Member]
Derivative Instruments [Member]
Defined Benefit Plan, Derivative [Member]
5.00% Series 11 Notes Due 2046 [Member]
Five Point Zero Zero Percent Series Eleven Notes Due Two Thousand Forty Six [Member]
Five Point Zero Zero Percent Series Eleven Notes Due Two Thousand Forty Six [Member]
Fixed-to-floating interest-rate swap
Fixed To Floating Interest Rate Swaps
Fixed To Floating Interest Rate Swaps
Level 2 [Member]
Fair Value, Inputs, Level 2 [Member]
Termination fee
Business Combination, Termination Fee
Business Combination, Termination Fee
Number of series of preferred stock
Number Of Series Of Preferred Stock
Number Of Series Of Preferred Stock
Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis]
Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis]
3.02% Series 43 Notes Due 2029 [Member]
Three Point Zero Two Percent Series Forty Three Notes Due Two Thousand Twenty Nine [Member]
Three Point Zero Two Percent Series Forty Three Notes Due Two Thousand Twenty Nine [Member]
Schedule Of Regulatory Assets And Liabilities [Table]
Schedule Of Regulatory Assets And Liabilities [Table]
Schedule Of Regulatory Assets And Liabilities [Table]
Subsequent Event [Line Items]
Subsequent Event [Line Items]
Public [Member]
The General Public [Member]
The General Public [Member]
Credit Facility [Domain]
Credit Facility [Domain]
New Accounting Pronouncements
Accounting Standards Update and Change in Accounting Principle [Text Block]
Distribution [Member]
Distribution Business Segment [Member]
Distribution Business Segment
Basic (in dollars per share)
Earnings Per Share, Basic
Expenditures
Environmental Expense and Liabilities
Contingencies
Contingencies Disclosure [Text Block]
Outsourcing and other agreements, Year 1
Outsourcing Agreements Future Minimum Payments Due in Next Twelve Months
Amount of required minimum payments under outsourcing agreements due in next twelve months.
Entity File Number
Entity File Number
Corporate Shares - Canadian [Member]
Debt Security, Corporate, US [Member]
Weighted-average remaining lease term (in years)
Operating Lease, Weighted Average Remaining Lease Term
Rate of compensation scale escalation (long-term)
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase
Net unfunded status
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position
Aged More Than 60 Days [Member]
Financing Receivables Equal To Greater Than 60 Days Past Due [Member]
Financing Receivables Equal To Greater Than 60 Days Past Due [Member]
Rate of cost of living increase
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Cost Of Living Increase
Defined benefit plan assumptions used calculating net periodic benefit cost rate of cost of living increase.
Common shares (Note 24)
Common shares
Common Stock, Value, Outstanding
Distributions to noncontrolling interest
Minority Interest Temporary Equity And Equity Decrease From Distributions To Noncontrolling Interest Holders
Minority interest temporary equity and equity decrease from distributions to noncontrolling interest holders.
Contributions received from sale of noncontrolling interest (Note 4)
Proceeds from Noncontrolling Interests
Dividends on common shares
Common share dividends
Dividends, Common Stock
Compensation expenses
Share-based Payment Arrangement, Expense
Electricity, US Regulated [Member]
Electricity, US Regulated [Member]
Long-term software/meter agreement, Year 3
Long Term Software and Meter Agreement Future Minimum Payments Due in Third Year
Amount of required minimum payments under Long term software and meter agreement due in third year.
Market Risk Credit Risk And Liquidity Risk [Table]
Market Risk Credit Risk And Liquidity Risk [Table]
Market Risk Credit Risk And Liquidity Risk [Table]
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets Disclosure [Abstract]
Environmental liabilities - beginning
Environmental liabilities - ending
Environmental Liabilities
Environmental Liabilities
Actuarial loss (gain)
Defined Benefit Plan Regulatory Assets Not Recognized As Components Of Net Periodic Benefit Costs Actuarial Loss
Components of regulatory assets that have not been recognized as components of net periodic benefit costs related to actuarial loss.
Document Annual Report
Document Annual Report
Commercial Paper Program [Member]
Commercial Paper [Member]
Other Long-Term Assets
Other Non-Current Assets [Text Block]
Other Non-Current Assets [Text Block]
Overheads capitalized for accounting but deducted for tax purposes
Overheads Capitalized for Accounting but Deducted for Tax Purposes
Overheads Capitalized for Accounting but Deducted for Tax Purposes
Category of Item Purchased [Axis]
Category of Item Purchased [Axis]
Retirement Benefits [Abstract]
Retirement Benefits [Abstract]
External Revenue Variance [Member]
External Revenue Variance [Member]
External Revenue Variance [Member]
Six Nations of the Grand River Development Corporation and Mississaugas of the Credit First Nation [Member]
Six Nations Of The Grand River Development Corporation And Mississaugas Of The Credit First Nation [Member]
Six Nations Of The Grand River Development Corporation And Mississaugas Of The Credit First Nation [Member]
Subsequent Event [Table]
Subsequent Event [Table]
Number of units outstanding, potentially unsettled (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Units Potentially Settled
Share-based Compensation Arrangement by Share-based Payment Award, Units Potentially Settled
Capital cost allowance in excess of depreciation and amortization
Deferred Tax Liabilities Capital Cost Allowance In Excess Of Depreciation And Amortization
Deferred Tax Liabilities Capital Cost Allowance In Excess Of Depreciation And Amortization
Contribution under the plan
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP
Schedule of Long-term Debt Instruments [Table]
Schedule of Long-term Debt Instruments [Table]
PWU Share Grant Plan [Member]
PWU Share Grant Plan [Member]
PWU Share Grant Plan [Member]
Noncontrolling interest (Note 28)
Noncontrolling interest - beginning balance, equity
Noncontrolling interest - ending balance, equity
Stockholders' Equity Attributable to Noncontrolling Interest
Cumulative preferred dividend rate (in cad per dollar)
Preferred Stock, Dividend Rate, Per-Dollar-Amount
Schedule of Weighted Average Assumptions Used to Determine Benefit Obligations
Schedule Of Weighted Average Assumptions Used To Determine Benefit Obligations [Table Text Block]
Schedule Of Weighted Average Assumptions Used To Determine Benefit Obligations
Investing activities
Net Cash Provided by (Used in) Investing Activities [Abstract]
Sales and disbursements
Defined Benefit Plan Fair Value Of Plan Assets Sales
Defined benefit plan fair value of plan assets sales.
Revaluation adjustment
Increase (decrease) of environmental liability due to revaluation adjustment
Increase Decrease In Revaluation Of Environmental Liabilities
Increase decrease in revaluation of environmental liabilities.
Other
Deferred Tax Liabilities, Other
Public Utilities, Regulatory Proceeding [Domain]
Public Utilities, Regulatory Proceeding [Domain]
Schedule of Defined Benefit Plans Disclosures [Table]
Schedule of Defined Benefit Plans Disclosures [Table]
Transmission revenue requirement
Public Utilities, Approved Transmission Rates, Revenue Requirement
Public Utilities, Approved Transmission Rates, Revenue Requirement
Schedule of Actuarial Gains and Losses and Prior Service Costs Recorded Within Regulatory Assets
Schedule Of Actuarial Gains And Losses And Prior Service Costs Recorded Within Regulatory Assets [Table Text Block]
Schedule Of Actuarial Gains And Losses And Prior Service Costs Recorded Within Regulatory Assets [Table Text Block]
Less: current portion
Environmental Liabilities Current Portion
Environmental liabilities current portion.
Debt Securities [Member]
Defined Benefit Plan, Debt Security [Member]
Total regulatory liabilities
Regulatory liabilities
Regulatory Liabilities
Accounts receivable
Increase (Decrease) in Accounts Receivable
Increase (decrease) in financing chargers
Increase Decrease In Financing Charges
Increase (decrease) in financing charges attributable to regulatory accounting.
Total liabilities, preferred shares, noncontrolling interest subject to redemption and equity
Liabilities and Equity
Summary of Fair Values and Carrying Values of Long-Term Debt
Schedule Of Fair Values And Carrying Values Of Long Term Debt[Table Text Block]
Tabular disclosure of information pertaining to fair value and carrying amount of long-term debt instruments or arrangements.
Years 6-10 [Member ]
Debt Instrument Maturity Period Between Six To Ten Years [Member ]
Debt Instrument Maturity Period Between Six To Ten Years [Member ]
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss), Net of Tax
Income Taxes
Income Tax Disclosure [Text Block]
Total long-term liabilities
Liabilities, Noncurrent
Portion at Fair Value Measurement [Member]
Portion at Fair Value Measurement [Member]
Purchase price adjustment
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred
Other commitment, Year 3
Other Commitment, to be Paid, Year Three
Other Regulatory Liabilities [Member]
Other Regulatory Liabilities [Member]
Other Regulatory Liabilities [Member]
Fair value of assets acquired and liabilities assumed
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net
Hedging Relationship [Axis]
Hedging Relationship [Axis]
Deferred income tax liabilities
Deferred Tax Liabilities, Gross [Abstract]
Line of Credit Facility [Line Items]
Line of Credit Facility [Line Items]
Current income tax expense
Current Income Tax Expense (Benefit)
Number of modified fair value options (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Modified Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Modified Fair Value
Deferred income tax recovery
Deferred Income Tax Expense (Benefit), Including OCI Amount
Deferred Income Tax Expense (Benefit), Including OCI Amount
Noncontrolling interest - beginning balance
Noncontrolling interest - ending balance
Minority Interest And Redeemable Noncontrolling Interest Equity And Temporary Equity
Minority Interest And Redeemable Noncontrolling Interest Equity And Temporary Equity
Average service life, intangible assets (in years)
Finite-Lived Intangible Asset, Useful Life
Equity Component [Domain]
Equity Component [Domain]
Derivative assets (Note 18)
Derivative Asset, Noncurrent
Hydro One Remote Communities [Member]
Hydro One Remote Communities [Member]
Hydro One Remote Communities [Member]
Effect of a 1% increase in health care cost trends
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation
Schedule of Estimated Future Benefit Payments
Schedule of Expected Benefit Payments [Table Text Block]
Defined Benefit Plan, Net Periodic Benefit, Type Of Cost (Credit) [Axis]
Defined Benefit Plan, Net Periodic Benefit, Type Of Cost (Credit) [Axis]
Defined Benefit Plan, Net Periodic Benefit, Type Of Cost (Credit)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Property, plant and equipment (Note 11)
Total
Property, Plant and Equipment, Net
Liability related to share based compensation
Deferred Compensation Liability, Classified, Noncurrent
Lessee, Lease, Description [Table]
Lessee, Lease, Description [Table]
Stock-Based Compensation
Share-based Payment Arrangement [Text Block]
Net income (loss)
Net Income (Loss) Attributable to Parent
Receivables Billing Status [Domain]
Receivables Billing Status [Domain]
Regulatory Matters [Table]
Regulatory Matters [Table]
Regulatory Matters [Table]
Short-term debt repaid (Note 4)
Repayments of Other Short-term Debt
Distributions paid to noncontrolling interest
Payments to Noncontrolling Interests
0.71% Series 48 Notes Due 2023 [Member]
Zero Point Seven One Percent Series Forty Eight Notes Due Two Thousand Twenty Three [Member]
Zero Point Seven One Percent Series Forty Eight Notes Due Two Thousand Twenty Three
Class A Units [Member]
Capital Unit, Class A [Member]
Total estimated future benefit payments through to 2030
Defined Benefit Plan Expected Future Benefit Payments
Defined benefit plan expected future benefit payments.
B2M Limited Partnership [Member]
Bruce to Milton Limited Partnership [Member]
Bruce to Milton Limited Partnership [Member]
Annual average rate of depreciation and amortization, property, plant and equipment
Average Depreciation and Amortization Rate
Average Depreciation and Amortization Rate
Current Fiscal Year End Date
Current Fiscal Year End Date
Outsourcing and other agreements, Year 5
Outsourcing Agreements Future Minimum Payments Due in Fifth Year
Amount of required minimum payments under outsourcing agreements due in fifth year.
2.97% Series 40 Notes Due 2025 [Member]
Two Point Nine Seven Percent Series Forty Notes Due Two Thousand Twenty Five [Member]
Two Point Nine Seven Percent Series Forty Notes Due Two Thousand Twenty Five [Member]
1.69% Series 49 Notes Due 2031 [Member]
One Point Six Nine Percent Series Forty Nine Notes Due Two Thousand Thirty One [Member]
One Point Six Nine Percent Series Forty Nine Notes Due Two Thousand Thirty One
Ontario Charging Network [Member]
Ontario Charging Network [Member]
Ontario Charging Network [Member]
Share Grants (number of common shares)
Number of Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Tax credit carryforwards
Deferred Tax Assets, Tax Credit Carryforwards
OEB [Member]
Ontario Energy Board [Member]
Ontario Energy Board [Member]
Fair value of options forfeited (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Fair Value
Liabilities:
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
1.76% Series 45 Notes Due 2025 [Member]
One Point Seven Six Percent Series Forty Five Notes Due Two Thousand Twenty Five [Member]
One Point Seven Six Percent Series Forty Five Notes Due Two Thousand Twenty Five
Equity [Member]
Equity [Member]
Life Expectancy At Age Forty Five [Member]
Life Expectancy At Age Forty Five [Member]
Life Expectancy At Age Forty Five [Member]
Pension and post-retirement benefit contributions in excess of pension expense
Pension Contributions in Excess of Pension Expense
Pension Contributions in Excess of Pension Expense
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information [Abstract]
Long-Lived Asset Impairment
Asset Impairment [Policy Text Block]
Asset Impairment Policy [Text Block]
Accounts Receivable and Allowance for Doubtful Accounts
Accounts Receivable And Allowance For Doubtful Accounts [Policy Text Block]
Accounts Receivable And Allowance For Doubtful Accounts Policy [Text Block]
Deferred Income Tax Assets And Liabilities [Table]
Deferred Income Tax Assets And Liabilities [Table]
Deferred Income Tax Assets And Liabilities [Table]
Business Acquisition, Acquiree [Domain]
Business Acquisition, Acquiree [Domain]
$300 million of MTN Series 39 notes [Member]
Three Hundred Million Of Medium Term Note Series Thirty Nine Notes [Member]
Three Hundred Million Of Medium Term Note Series Thirty Nine Notes [Member]
Peterborough Distribution Inc. [Member]
Peterborough Distribution Inc. [Member]
Peterborough Distribution Inc. [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment [Line Items]
Benefits paid
Defined Benefit Plan, Benefit Obligation, Benefits Paid
Permissible limit on debt to total capital, percentage
Debt Instrument Covenant Debt To Capital Percentage
Debt instrument covenant debt to capital percentage.
Schedule of Property, Plant and Equipment
Property, Plant and Equipment [Table Text Block]
Account receivable, percentage
Account Receivable Net Percentage
Account Receivable Net Percentage
PBO [Member]
Projected Benefit Obligation [Member]
Projected Benefit Obligation [Member]
Other Commitments [Domain]
Other Commitments [Domain]
Polychlorinated Biphenyl Liability [Member]
Polychlorinated Biphenyl Liability [Member]
Polychlorinated Biphenyl Liability [Member]
Common shares issued
Stock Issued During Period, Shares, New Issues
Hedged portion of debt
Hedged Portion of Long-Term Debt
Hedged portion of long-term debt.
Intangible Assets
Finite-Lived Intangible Assets, Gross
Summary of Company's Capital Structure
Schedule of Capitalization [Table Text Block]
Fair Value Inputs Assets Liabilities Quantitative Information [Table]
Fair Value Inputs Assets Liabilities Quantitative Information [Table]
Fair value inputs assets liabilities quantitative information.
Short-term Securities [Member]
Money Market Funds [Member]
Schedule of Effect of One Percent Change in Health Care Cost Trends on Service Cost and Interest Cost
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]
Accumulated Depreciation
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment
Unrealized loss on Foreign-Exchange Contract included in financing charges (Note 4)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings
Preferred shares (Note 24)
Preferred shares
Preferred Stock, Value, Outstanding
Aggregate intrinsic value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value
Related Party [Member]
Related Party [Member]
Related Party [Member]
Schedule of Benefit Obligations and Plan Assets
Schedule Of Balance Sheet Presentation Of Net Benefit Liabilities [Table Text Block]
Tabular disclosure of pension and post-retirement and post-employment benefits based on balance sheet presentation.
Related Party Transactions [Abstract]
Related Party Transactions [Abstract]
Convertible debentures redeemed (Note 4)
Repayments of convertible debt
Repayments of Convertible Debt
IESO [Member]
Independent Electricity System Operator [Member]
Independent Electricity System Operator [Member]
Hedging Relationship [Domain]
Hedging Relationship [Domain]
Schedule of Future Minimum Operating Lease Payments After Adoption
Lessee, Operating Lease, Liability, Maturity [Table Text Block]
2020-2022 Transmission Decision [Member]
2020-2022 Transmission Decision [Member]
2020-2022 Transmission Decision
Acquisitions and Goodwill
Acquisitions and Goodwill [Policy Text Block]
Acquisitions and Goodwill Policy [Text Block]
Basis of Accounting
Basis of Accounting, Policy [Policy Text Block]
Other
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount
Long Term Incentive Plan [Member]
Long Term Incentive Plan [Member]
Long Term Incentive Plan [Member]
Basic (in shares)
Weighted Average Number of Shares Outstanding, Basic
2021 Approved Revenue Requirement [Member]
Two Thousand Twenty-One Approved Revenue Requirement [Member]
Two Thousand Twenty-One Approved Revenue Requirement [Member]
Ownership [Axis]
Ownership [Axis]
Document Information [Line Items]
Document Information [Line Items]
Commitments [Line Items]
Commitments [Line Items]
Commitments [Line Items]
Long-term debt, Total
Long Term Debt Carrying Amount
Carrying amount of debt instrument, before unamortized (discount) premium, debt issuance costs, and unrealized mark-to-market gains and losses, of long-term debt.
3.64% Series 44 Notes Due 2050 [Member]
Three Point Six Four Percent Series Forty Four Notes Due Two Thousand Twenty Fifty [Member]
Three Point Six Four Percent Series Forty Four Notes Due Two Thousand Twenty Fifty [Member]
Male [Member]
Male [Member]
Male [Member]
Regulatory assets
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Regulatory Assets
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Regulatory Assets
Outsourcing and other agreements, Year 4
Outsourcing Agreements Future Minimum Payments Due in Fourth Year
Amount of required minimum payments under outsourcing agreements due in fourth year.
Cash Flow Hedging [Member]
Cash Flow Hedging [Member]
Carrying Value [Member]
Reported Value Measurement [Member]
Plan Name [Domain]
Plan Name [Domain]
Capital cost allowance in excess of depreciation and amortization
Capital Cost Allowance in Excess of Depreciation and Amortization
Capital Cost Allowance in Excess of Depreciation and Amortization
Pension Benefit Regulatory Asset [Member]
Pension Costs [Member]
Net actuarial loss (gain)
Actuarial loss (gain) for the year
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)
Fair Value
Long-term debt, including current portion
Long-term Debt, Fair Value
Cash and Cash Equivalents
Cash and Cash Equivalents, Policy [Policy Text Block]
Schedule of Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Schedule Of Weighted Average Assumptions Used In Calculating Net Periodic Benefit Costs [Table Text Block]
Schedule Of Weighted Average Assumptions Used In Calculating Net Periodic Benefit Costs
Income tax recovery (Note 7)
Total income tax recovery
Income Tax Expense (Benefit)
Interest capitalized for accounting but deducted for tax purposes
Interest Capitalized for Accounting but Deducted for Tax Purposes
Interest Capitalized for Accounting but Deducted for Tax Purposes
Cash and cash equivalents, beginning of year
Cash and cash equivalents, end of year
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents
Capital Units by Class [Axis]
Capital Units by Class [Axis]
Transmission [Member]
Transmission Business Segment [Member]
Transmission Business Segment
Property, Plant and Equipment
Property, Plant and Equipment, Policy [Policy Text Block]
Long-term software/meter agreement, Year 4
Long Term Software and Meter Agreement Minimum Payments Due in Fourth Year
Amount of required minimum payments under Long term software and meter agreement due in fourth year.
Title of Individual [Domain]
Title of Individual [Domain]
4.29% Series 30 Notes Due 2064 [Member]
Four Point Twenty Nine Percent Series Thirty Notes Due Two Thousand Sixty Four [Member]
Four Point Twenty Nine Percent Series Thirty Notes Due Two Thousand Sixty Four [Member]
Local Phone Number
Local Phone Number
Acquisitions (Note 4)
Cash payment to acquire business
Payments to Acquire Businesses, Gross
Long term purchase agreement renewal term (in years)
Long Term Purchase Commitment Renewal Term
Long term purchase commitment renewal term.
Aggregate intrinsic value of options exercised
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value
Number of bilateral credit facilities
Number Of Bilateral Credit Facilities
Number Of Bilateral Credit Facilities
Revenue from acquiree
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual
Pension plan
Defined Benefit Plan, Plan Assets, Employer, Related Party, Amount
Address Type [Domain]
Address Type [Domain]
Employee Stock Ownership Plan (ESOP) Name [Axis]
Employee Stock Ownership Plan (ESOP) Name [Axis]
Related Party Transaction [Domain]
Related Party Transaction [Domain]
Schedule of Finite-Lived Intangible Assets [Table]
Schedule of Finite-Lived Intangible Assets [Table]
New pension plan average pensionable earnings (in years)
Defined Benefit Plan New Average Pensionable Earnings
Defined benefit plan new average pensionable earnings.
Maximum borrowing capacity
Total Amount
Line of Credit Facility, Maximum Borrowing Capacity
Award Type [Axis]
Award Type [Axis]
Weighted average discount rate
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate
Short-term notes payable (Note 17)
Short-term notes payable
Commercial Paper
Other long-term liabilities
Other Liabilities, Miscellaneous, Noncurrent
Other Liabilities, Miscellaneous, Noncurrent
Materials and supplies
Inventory, Raw Materials and Supplies, Gross
Retained Earnings [Member]
Retained Earnings [Member]
Preferred shares outstanding (in shares)
Preferred Stock, Shares Outstanding
2023
Estimated Future Environmental Expenditures Due In Three Years
Estimated future environmental expenditures due in three year.
Revaluation adjustment
Asset Retirement Obligation, Revision of Estimate
Measurement Basis [Axis]
Measurement Basis [Axis]
$50 Million of MTN Series 33 Notes [Member]
Fifty Million Of Medium Term Note Series Thirty Three Notes One [Member]
Fifty Million of Medium Term Note Series Thirty Three Notes One [Member]
Short-term notes repaid
Repayments of Commercial Paper
Components of Net Periodic Benefit Costs
Schedule of Net Benefit Costs [Table Text Block]
Regulatory Accounting
Regulatory Accounting [Policy Text Block]
Regulatory Accounting Policy [Text Block]
Significant Accounting Policies
Significant Accounting Policies [Text Block]
Net cash used in investing activities
Net Cash Provided by (Used in) Investing Activities
Long-term software/meter agreement, Year 5
Long Term Software and Meter Agreement Future Minimum Payments Due in Fifth Year
Amount of required minimum payments under Long term software and meter agreement due in fifth year.
Approximate Life Expectancies Used to Determine Projected Benefit Obligations for Pension, Post-Retirement and Post-Employment Plans
Life Expectancies Used To Determine Projected Benefit Obligations For Pension And Post Employment Plans [Table Text Block]
Life Expectancies Used To Determine Projected Benefit Obligations For Pension And Post Employment Plans [Table Text Block]
Contractual term (in years)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term
Change in Projected Benefit Obligation and Change in Plan Assets
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]
Award Type [Domain]
Award Type [Domain]
Accrued liabilities
Liability, Defined Benefit Plan, Current
Long-term liabilities:
Liabilities, Noncurrent [Abstract]
Corporate Debt Securities [Member]
Corporate Debt Securities [Member]
3.72% Series 38 Notes Due 2047 [Member]
Three Point Seven Two Percent Series Thirty Eight Notes Due Two Thousand Forty Seven [Member]
Three point seven two percent series thirty eight notes due two thousand forty seven.
Preferred shares redeemed (Note 24)
Payments for Repurchase of Redeemable Preferred Stock
Property, Plant and Equipment
Property, Plant and Equipment Disclosure [Text Block]
OEFC [Member]
Ontario Electricity Financial Corporation [Member]
Ontario Electricity Financial Corporation [Member]
Document Registration Statement
Document Registration Statement
Due to related parties
Increase (Decrease) in Due to Related Parties, Current
Earnings Per Common Share
Earnings Per Share [Text Block]
Pension Benefits [Member]
Pension Plan [Member]
Weighted average discount rate
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate
Add: Net unamortized debt premiums
Debt Instrument, Unamortized Premium, Current
Noncontrolling interest subject to redemption (Note 28)
Noncontrolling interest - beginning balance, temporary equity
Noncontrolling interest - ending balance, temporary equity
Redeemable Noncontrolling Interest, Equity, Carrying Amount
Current liabilities:
Liabilities, Current [Abstract]
Statutory income tax rate
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
Deferred Tax Asset Sharing [Member]
Deferred Tax Asset Sharing [Member]
Deferred Tax Asset Sharing
New Accounting Pronouncements
New Accounting Pronouncements, Policy [Policy Text Block]
Statement of Financial Position [Abstract]
Statement of Financial Position [Abstract]
EPS
Earnings Per Share, Basic [Abstract]
Year 2 [Member]
Debt Instrument Maturity Period Year Two [Member]
Debt Instrument Maturity Period Year Two [Member]
Materials and supplies
Increase (Decrease) in Materials and Supplies