Accounts Payable And Accrued Liabilities Current Accounts payable and accrued liabilities (note 7) Accrued Income Taxes Current Income taxes payable Accumulated Depreciation Depletion And Amortization Property Plant And Equipment less accumulated depreciation and depletion Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income Loss [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income Loss Net Of Tax September 30 balance January 1 balance Accumulated other comprehensive income (note 9) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income Loss [Table] Accumulated Other Comprehensive Income (Loss) [Table] Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Adjustment for non-cash items: Amendment Flag Amendment Flag Asset Retirement Obligation And Other Environmental Liabilities Current Asset Retirement Obligation And Other Environmental Liabilities Current Asset retirement obligations and other environmental liabilities in current liabilities Asset retirement obligation and other environmental liabilities, noncurrent. Asset Retirement Obligation And Other Environmental Liabilities Noncurrent Asset retirement obligations and other environmental liabilities Assets Total assets as at September 30 TOTAL ASSETS Assets [Abstract] ASSETS Assets Current Total current assets Assets Current [Abstract] Current assets Basis Of Presentation And Significant Accounting Policies [Text Block] Basis of financial statement preparation Book Value of Assets Sold Book Value Of Assets Sold Book value of assets sold Sum of exploration expenses, additions to property, plant, equipment and intangible and additions to capital leases. Capital And Exploration Expenditures CAPEX Capital Lease Obligations Noncurrent Capital leases Cash And Cash Equivalents At Carrying Value CASH AT END OF PERIOD CASH AT BEGINNING OF PERIOD Cash Cash And Cash Equivalents Period Increase Decrease INCREASE (DECREASE) IN CASH Chemical [Member] Chemical [Member] Chemical Common Stock Dividends Per Share Declared Dividends per common share (dollars) Common Stock Shares Authorized Common shares authorized Common Stock Shares Outstanding Common shares outstanding Common Stock Value Common shares at stated value Comprehensive Income Net Of Tax Comprehensive income Comprehensive Income Note [Text Block] Other comprehensive income information Corporate And Other [Member] Corporate and Other Costs And Expenses TOTAL EXPENSES TOTAL EXPENSES Costs And Expenses [Abstract] EXPENSES Purchase cost of crude oil, products and other raw materials, feedstocks, semi finished products, finished products and other merchandise that become part of salable products for oil and gas, refining and marketing and chemical operations. Crude Oil And Product Purchases Purchases of crude oil and products Crude Oil And Product Purchases, Related Parties Crude Oil And Product Purchases Related Parties Amounts to related parties included in purchases of crude oil and products Current Fiscal Year End Date Current Fiscal Year End Date Debt Current Notes and loans payable Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument Maturity Date Debt instrument, maturity date Debt Instrument [Table] Schedule of Long-term Debt Instruments [Table] Deferred Compensation Sharebased Arrangements Liability Classified Noncurrent Share-based incentive compensation liabilities The component of income tax expense for the period representing the net change in the entity's deferred tax assets and liabilities pertaining to continuing operations. Prior year Exploration and Exploratory dry hole costs written off as expense in the current year. Entity's net proportionate share for the period of net earnings, less dividends, of its investment to which the equity method of accounting is applied. Deferred Income Taxes And Other Deferred income taxes and other Deferred Tax Assets Net Current Deferred income tax assets Deferred Tax Liabilities Noncurrent Deferred income tax liabilities Defined Benefit Plan Amortization Of Gains Losses Amortization of actuarial loss Defined Benefit Plan Amortization Of Prior Service Cost Credit Amortization of prior service cost Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Expected Return On Plan Assets Expected return on plan assets Defined Benefit Plan Interest Cost Interest cost Defined Benefit Plan Net Periodic Benefit Cost Net benefit cost Defined Benefit Plans Disclosures Defined Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans [Domain] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan Service Cost Current service cost Depreciation Depletion And Amortization Depreciation and depletion Disclosure - Business Segments [Abstract] Disclosure Business Segments [Abstract] Disclosure - Business Segments [Abstract] Disclosure - Calculation of Net Income Per Share [Abstract] Disclosure Calculation Of Net Income Per Share [Abstract] Disclosure - Calculation of Net Income Per Share [Abstract] Disclosure - Gains And Losses On Asset Sales [Abstract] Disclosure Gains And Losses On Asset Sales [Abstract] Disclosure - Gains And Losses On Asset Sales [Abstract] Disclosure - Income Tax Expense/(Credit) For Components Of Comprehensive Income [Abstract] Disclosure Income Tax Expense Credit For Components Of Comprehensive Income [Abstract] Disclosure - Income Tax Expense/(Credit) For Components Of Comprehensive Income [Abstract] Disclosure - Long Term Debt [Abstract] Disclosure Long Term Debt [Abstract] Disclosure - Long Term Debt [Abstract] Disclosure - Long-term debt - Additional Information [Abstract] Disclosure Longterm Debt Additional Information [Abstract] Disclosure - Long-term debt - Additional Information [Abstract] Disclosure - Other Long-Term Obligations [Abstract] Disclosure Other Long Term Obligations [Abstract] Disclosure - Other Long-Term Obligations [Abstract] Disclosure - Schedule Of Components Of Net Benefit Cost [Abstract] Disclosure Schedule Of Components Of Net Benefit Cost [Abstract] Disclosure - Schedule Of Components Of Net Benefit Cost [Abstract] Disclosure - Schedule Of Financing Costs [Abstract] Disclosure Schedule Of Financing Costs [Abstract] Disclosure - Schedule Of Financing Costs [Abstract] Disclosure - Total Comprehensive Income [Abstract] Disclosure Total Comprehensive Income [Abstract] Disclosure - Total Comprehensive Income [Abstract] Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Information [Line Items] Document Information [Line Items] Document Period End Date Document Period End Date Document Type Document Type Downstream [Member] Downstream [Member] Downstream Due To Related Parties Current Accounts payable and accrued liabilities, related parties Due To Related Parties Noncurrent Long-term debt due to related parties, noncurrent Earnings Per Share [Abstract] PER SHARE INFORMATION (Canadian dollars) Earnings Per Share Basic Net income per common share (dollars) Net income per common share - basic (dollars) (note 8) Earnings Per Share Basic And Diluted [Line Items] Earnings Per Share Basic And Diluted [Line Items] Earnings Per Share Basic And Diluted [Line Items] Earnings Per Share Basic [Member] Earnings Per Share, Basic Earnings Per Share Diluted Net income per common share (dollars) Net income per common share - diluted (dollars) (note 8) Earnings Per Share Diluted [Member] Earnings Per Share, Diluted Earnings Per Share [Text Block] Net income per share Eliminations Eliminations [Member] Eliminations Entities [Table] Entities [Table] Entity Central Index Key Entity Central Index Key Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Entity [Domain] Entity [Domain] Entity Filer Category Entity Filer Category Entity Registrant Name Entity Registrant Name Exploration Expense Exploration The amount of federal excise tax included in sales and revenues, which are then deducted as an expense. Federal Excise Tax Federal excise tax Federal excise tax included in operating revenues Finite Lived Intangible Assets Net Other intangible assets, net Goodwill Goodwill Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest INCOME BEFORE INCOME TAXES Income Statement [Abstract] Income Statement [Abstract] Income Tax Expense Benefit INCOME TAXES Increase Decrease In Accounts Payable And Accrued Liabilities Accounts payable and accrued liabilities Increase Decrease In Accounts Receivable Accounts receivable Increase Decrease In Accrued Income Taxes Payable Income taxes payable The net change during the reporting period in the aggregate value of all inventory, materials and supplies held by the reporting entity, associated with underlying transactions that are classified as operating activities. And the net change during the reporting period in the amount of outstanding money paid in advance for goods or services that bring economic benefits for future periods. Increase Decrease In Inventories Materials And Supplies And Prepaids Inventories, materials, supplies and prepaid expenses Increase Decrease In Operating Capital [Abstract] Changes in operating assets and liabilities: Increase Decrease In Other Operating Capital Net All other items - net Interest And Debt Expense Debt related interest Interest Expense Financing costs Total financing costs Financing costs (note 5) Interest Expense Debt Net interest expense Disclosure of interest expense. Interest Expense Disclosure [Text Block] Financing costs Interest Expense Other Other interest Interest Paid Capitalized Capitalized interest Inventory Finished Goods And Work In Process Inventories of crude oil and products Details of investment and other income including the aggregate before and after tax gain (loss) on the proceeds from the sale of assets (including subsidiaries, cost and equity method investments and property, plant and equipment) over book value. Investment And Other Income Details [Text Block] Investment and other income Investment And Other Income [Line Items] Investment And Other Income [Line Items] Investment And Other Income [Line Items] Investment And Other Income [Table] Investment And Other Income [Table] Investment And Other Income [Table] Gains and losses on disposal of assets. Interest income represents earnings which reflect the time value of money or transactions in which the payments are for the use or forbearance of money. Entity's net proportionate share for the period of the undistributed net income (loss) of its investment to which the equity method of accounting is applied. Other income reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement due to materiality considerations. Investment Income And Other Investment and other income Investment and other income (note 3) Legal Entity [Axis] Legal Entity [Axis] Liabilities TOTAL LIABILITIES Liabilities [Abstract] LIABILITIES Liabilities And Stockholders Equity TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities Current Total current liabilities Liabilities Current [Abstract] Current liabilities Line Of Credit Facility [Line Items] Line of Credit Facility [Line Items] Line Of Credit Facility Maximum Borrowing Capacity Line of Credit maximum borrowing capacity Line Of Credit Facility [Table] Line of Credit Facility [Table] Long Term Debt And Capital Lease Obligations Long-term debt (note 6) Total long-term debt Long Term Debt Noncurrent Long-term debt Long Term Debt [Text Block] Long-term debt Long Term Investments And Receivables Net Long-term receivables, investments and other long-term assets Carrying amount as of the balance sheet date for elements of machinery or equipment held for the purpose of replacing similar parts in the course of repair or maintenance. Expenditures made in advance of when the economic benefit of the cost will be realized, and which will be expensed in future periods with the passage of time or when a triggering event occurs. Materials Supplies And Prepaid Expenses Materials, supplies and prepaid expenses Net Cash Provided By Used In Financing Activities CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES Net Cash Provided By Used In Financing Activities [Abstract] FINANCING ACTIVITIES Net Cash Provided By Used In Investing Activities CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES Net Cash Provided By Used In Investing Activities [Abstract] INVESTING ACTIVITIES Net Cash Provided By Used In Operating Activities Cash flows from (used in) operating activities CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES Net Cash Provided By Used In Operating Activities [Abstract] OPERATING ACTIVITIES Net gain (loss) on asset sales, after tax. Net Gain Loss On Asset Sales After Tax Gain/(loss) on asset sales, after tax Cash flow adjustment for the noncash net gain (loss) included in net income from sales of assets, including subsidiaries, cost and equity method investments and property, plant and equipment. Proceeds from asset sales are reported as an investing activity. Net Gain Loss On Asset Sales Before Tax Gain/(loss) on asset sales, before tax Cash flow adjustment for the noncash net (gain) included in net income from sales of assets, including subsidiaries, cost and equity method investments and property, plant and equipment. Proceeds from asset sales are reported as an investing activity. Net Gain On Asset Sales (Gain)/loss on asset sales (note 3) Net Income Loss Net income NET INCOME Net income (millions of dollars) Total revenue from sales of goods and services during the reporting period, reduced by sales returns and allowances and sales discounts. Also includes federal excise tax which is then deducted as an expense. Operating Revenues Including Federal Excise Tax Operating revenues Other Comprehensive Income Amortization Of Defined Benefit Plan Net Prior Service Cost Recognized In Net Periodic Pension Cost Tax Amortization of post-retirement benefit liability adjustment included in net periodic benefit cost Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax Current period change excluding amounts reclassified from accumulated other comprehensive income Post-retirement benefit liability adjustment (excluding amortization) Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Pension Cost Net Of Tax Amounts reclassified from accumulated other comprehensive income Amortization of post-retirement benefit liability adjustment included in net periodic benefit costs Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Total other comprehensive income/(loss) Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent [Abstract] Other comprehensive income, net of income taxes Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax Post-retirement benefits liability adjustment (excluding amortization) Other Comprehensive Income Loss Tax Post-retirement benefits liability adjustments, Total Schedule of the gain or loss, before and after tax on sales of assets, including subsidiaries, cost and equity method investments and property, plant and equipment. Other Income Detail [Text Block] Gains And Losses On Asset Sales Other Liabilities Disclosure [Text Block] Other long-term obligations Other Liabilities Noncurrent Other long-term obligations (note 7) Total other long-term obligations Schedule of long term obligations including employee retirement benefits, asset retirement obligations and other environmental liabilities, share based incentive compensation, and other obligations not otherwise itemized that are due beyond one year (or operating cycle, if longer) from the balance sheet date. Other Noncurrent Liabilities Table [Text Block] Other Long-Term Obligations Other noncurrent obligations. Other Noncurrent Obligations Other obligations Other Postretirement Benefit Plans Defined Benefit [Member] Other post-retirement benefits Payments For Repurchase Of Common Stock Common shares purchased Payments Of Dividends Common Stock Dividends paid Payments To Acquire Productive Assets Additions to property, plant and equipment Pension And Other Postretirement Benefits Disclosure [Text Block] Employee retirement benefits Pension And Other Postretirement Defined Benefit Plans Current Liabilities Employee retirement benefits obligations in current liabilities Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent Employee retirement benefits Pension Contributions Included contribution to registered pension plans Pension Plans Defined Benefit [Member] Pension benefits Proceeds From Issuance Of Long Term Debt Long-term debt issued Proceeds From Payments For Long Term Loans For Related Parties Repayment of loan from equity company Proceeds From Repayments Of Short Term Debt Short-term debt - net The cash inflow from the sale of subsidiaries, cost and equity method investments and property, plant and equipment. Proceeds From Sales Of Assets Proceeds from asset sales Proceeds From Stock Options Exercised Issuance of common shares under stock option plan Costs, excluding deprecation, incurred to operate and maintain - 1) oil and gas wells, production, transportation and support equipment and facilities; 2) refining manufacturing facilities; and 3) chemical manufacturing facilities. Production And Manufacturing Expenses Production and manufacturing Production And Manufacturing Expenses, Related Parties Production And Manufacturing Expenses Related Parties Amounts to related parties included in production and manufacturing expenses Property Plant And Equipment Gross Property, plant and equipment, Property Plant And Equipment Net Property, plant and equipment, net Receivables Net Current Accounts receivable, less estimated doubtful accounts Repayments Of Long Term Capital Lease Obligations Reduction in capitalized lease obligations Retained Earnings Accumulated Deficit Earnings reinvested Revenue From Related Parties Amounts from related parties included in operating revenues Revenues Export sales to the United States Revenues [Abstract] REVENUES AND OTHER INCOME Revenues From Transactions With Other Operating Segments Of Same Entity Intersegment sales Schedule Of Accumulated Other Comprehensive Income Loss Table [Text Block] Schedule Of Changes In Accumulated Other Comprehensive Income Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share Table [Text Block] Earnings Per Share Computation Schedule Of Debt Instruments [Text Block] Long-Term Debt Schedule Of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Schedule Of Earnings Per Share Basic And Diluted [Table] Schedule Of Earnings Per Share Basic And Diluted [Table] Schedule Of Earnings Per Share Basic And Diluted [Table] Schedule of financing cost Schedule Of Financing Cost [Text Block] Schedule Of Financing Costs Schedule Of Income Tax Expense For Components Of Comprehensive Income Schedule Of Income Tax Expense For Components Of Comprehensive Income Table [Text Block] Schedule Of Income Tax Expense (Credit) For Components Of Other Comprehensive Income Schedule Of Net Benefit Costs Table [Text Block] Schedule Of Components Of Net Benefit Cost Schedule of Other Liabilities [Line Items] Schedule Of Other Liabilities [Line Items] Schedule of Other Liabilities [Line Items] Schedule of Other Liabilities [Table] Schedule Of Other Liabilities [Table] Schedule of Other Liabilities [Table] Schedule Of Segment Reporting Information By Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule Of Segment Reporting Information By Segment [Text Block] Business Segments Segment [Domain] Segment [Domain] Segment Reporting Disclosure [Text Block] Business Segments Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Segment Reporting Information Revenue TOTAL OPERATING REVENUES, INTERSEGMENT SALES, INVESTMENT AND OTHER INCOME Selling General And Administrative Expense Selling and general Statement Business Segments [Axis] Business Segments [Axis] Statement [Line Items] Statement [Line Items] Statement Of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Statement Of Financial Position [Abstract] Statement of Financial Position [Abstract] Statement Of Income And Comprehensive Income [Abstract] Statement of Other Comprehensive Income [Abstract] Statement [Table] Statement [Table] Stockholders Equity [Abstract] SHAREHOLDERS' EQUITY Stockholders Equity Including Portion Attributable To Noncontrolling Interest TOTAL SHAREHOLDERS' EQUITY Text Block [Abstract] Text Block [Abstract] Total revenues and income from equity affiliates and other income. Total Revenues And Other Income TOTAL REVENUES AND OTHER INCOME Trading Symbol Trading Symbol