XML 114 R43.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Significant Accounting Policies [Line Items]
Amortization of computer software development costs, in years	15 years
Amortization of customer lists, in years	10 years
Refinery And Chemical Process
Significant Accounting Policies [Line Items]
Property plant and equipment, useful life	25 years
Maximum | Mining Heavy Equipment
Significant Accounting Policies [Line Items]
Property plant and equipment, useful life	15 years
Maximum | Ore Processing Plant Assets
Significant Accounting Policies [Line Items]
Property plant and equipment, useful life	50 years
Syncrude Joint Venture
Significant Accounting Policies [Line Items]
Undivided interest in oil and gas activities	25.00%
Kearl Joint Venture
Significant Accounting Policies [Line Items]
Undivided interest in oil and gas activities	70.96%

X

- Definition

Amortization of computer software development costs

+ References

No definition available.

+ Details

Name:	imo_AmortizationOfComputerSoftwareDevelopmentCosts
Namespace Prefix:	imo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

Name:	imo_SignificantAccountingPoliciesLineItems
Namespace Prefix:	imo_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Undivided interest in oil and gas activities conducted jointly with third parties.

+ References

No definition available.

+ Details

Name:	imo_UndividedInterestInOilAndGasActivities
Namespace Prefix:	imo_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=imo_RefineryAndChemicalProcessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=imo_MiningHeavyEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=imo_OreProcessingPlantAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=imo_SyncrudeJointVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=imo_KearlJointVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: