Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Notes to Consolidated Financial Statements [Abstract]
Summary of Provision for Income Taxes	2021   2020 Current income tax       Tax expense (recovery) for current year 1,033     (38) Adjustments in respect of prior years (13)   (30) Total current income tax expense (recovery) 1,020     (68) Deferred income tax       Origination and reversal of temporary differences (30)   72   Adjustments in respect of prior years 6     (58) Change in recognition of tax losses and deductible temporary differences (6)   (20) Impact of tax rate changes (1)   (3) Total deferred income tax recovery (31)   (9) Income tax expense (recovery) included in net earnings 989     (77)
Summary of Total Income Tax Expense	The provision for income taxes differs from the amount that would have resulted from applying the Canadian statutory income tax rates to earnings (loss) before income taxes as follows:     2021   2020 Earnings (loss) before income taxes       Canada 1,884     525   United States 1,319     (506) Trinidad 256     (44) Australia 204     83   Other 505     324     4,168     382   Canadian federal and provincial statutory income tax rate (%) 27     27   Income tax at statutory rates 1,125     103   Adjusted for the effect of:       Impact of foreign tax rates (98)   (18) Production-related deductions (24)   (12) Non-taxable income (18)   (59) Change in recognition of tax losses and deductible temporary differences (6)   (20) Recovery of prior year taxes due to US legislative changes (4)   (94) Non-deductible expenses 12     13   Foreign accrual property income 2     7   Other ‐     3   Income tax expense (recovery) included in net earnings 989     (77)
Summary of Deferred Income Tax Assets (Liabilities)	Deferred Income Taxes   In respect of each type of temporary difference, unused tax loss and unused tax credit, the amounts of deferred tax assets and liabilities recognized in the consolidated balance sheets as at December 31 and the amount of the deferred tax (recovery) expense   recognized in net earnings were:             Deferred Income Tax (Recovery)   Deferred Income Tax (Assets)   Expense Recognized   Liabilities   in Net Earnings   2021   2020   2021   2020 Deferred income tax assets               Asset retirement obligations and accrued environmental costs (354)   (376)   21     20   Tax loss and other carryforwards (297)   (370)   75     (98) Pension and other post-retirement benefit liabilities (178)   (161)   (45)   (12) Lease liabilities (151)   (201)   47     26   Long-term debt (140)   (102)   (39)   3   Inventories (126)   (37)   (90)   20   Receivables (44)   (50)   6     2   Payables and accrued charges (14)   ‐     (14)   25   Other assets (1)   (12)   11     17   Deferred income tax liabilities               Property, plant and equipment 3,765     3,637     132     (12) Goodwill and other intangible assets 404     471     (64)   (67) Payables and accrued charges ‐     72     (72)   72   Other liabilities 39     36     1     (5)   2,903    2,907   ( 31 ) (9)
Summary of Reconciliation of Net Deferred Income Tax Liabilities	Reconciliation of net deferred income tax liabilities:     2021   2020 Balance – beginning of year 2,907     2,896   Income tax recovery recognized in net earnings (31)   (9) Income tax charge recognized in other comprehensive income ("OCI") 30     17   Other (3)   3   Balance – end of year 2,903    2,907
Summary of Amounts and Expiry Dates of Unused Tax Losses and Unused Tax Credits	Amounts and expiry dates of unused tax losses and unused tax credits as at December 31, 2021, were:     Amount   Expiry Date Unused federal operating losses 1,206     2022 – Indefinite Unused federal capital losses 589     Indefinite Unused investment tax credits 22     2022 – 2040