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.

No definition available.

Name:	imo_OperatingRevenuesIncludingFederalExciseTax
Namespace Prefix:	imo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Business Segments (Parenthetical) (Detail) - CAD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounts payable and accrued liabilities
Segment Reporting Information [Line Items]
Non-cash adjustments to accrued liabilities and all other items			$ 570
United States Exports
Segment Reporting Information [Line Items]
Operating revenues	$ 1,373	$ 1,664