Post-Employment Benefits - Summary of Expected Future Benefit Payments (Detail) - Canada plan [member] $ in Millions	Oct. 31, 2020 CAD ($)
Disclosure of defined benefit plans [line items]
2020	$ 391
2021	396
2022	384
2023	391
2024	398
2025-2029	2,116
Total	4,076
Pension plan [member]
Disclosure of defined benefit plans [line items]
2020	363
2021	367
2022	354
2023	360
2024	367
2025-2029	1,953
Total	3,764
Other post employment benefit plans [member]
Disclosure of defined benefit plans [line items]
2020	28
2021	29
2022	30
2023	31
2024	31
2025-2029	163
Total	$ 312

Defined benefit plan expected future benefit payment after five through ten years.

No definition available.

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPaymentAfterFiveThroughTenYears
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined benefit plan expected future benefit payments in year five.

+ References

No definition available.

+ Details

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPaymentYearFive
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined benefit plan expected future benefit payments year four.

+ References

No definition available.

+ Details

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPaymentYearFour
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined benefit plan expected future benefit payments year three

+ References

No definition available.

+ Details

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPaymentYearThree
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined benefit plan expected future benefit payments year two.

+ References

No definition available.

+ Details

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPaymentYearTwo
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined benefit plan expected future benefit payments

+ References

No definition available.

+ Details

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPayments
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined benefit plan expected future benefit payments next twelve months.

+ References

No definition available.

+ Details

Name:	cm_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths1
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfDefinedBenefitPlansLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_DefinedBenefitPlansAxis=cm_DomesticDefinedBenefitPlans1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cm_DefinedBenefitPlansByNameAxis=cm_PensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cm_DefinedBenefitPlansByNameAxis=cm_OtherPostEmploymentBenefitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: