Structured Entities - Additional Information (Detail) - CAD ($) $ in Millions	12 Months Ended
Oct. 31, 2025	Oct. 31, 2024
Disclosure of information about structured entities [Line Items]
Fair value of transferred financial assets that are not derecognised in their entirety	$ 17,209	$ 16,118
Associated liabilities	16,815	15,598
NHA MBS US Agency MBS And CMO [member]
Disclosure of information about structured entities [Line Items]
Fair value of transferred financial assets that are not derecognised in their entirety	31,264	19,903
Trading securities [member]
Disclosure of information about structured entities [Line Items]
Mortgage backed securities at fair value	784	1,582
Other Securitization Vehicles [Member]
Disclosure of information about structured entities [Line Items]
Sale of CMBS to securitization vehicles	2,111	1,730
Gain or loss on sale of mortgage backed securities	24	19
Other Securitization Vehicles [Member] \| Financial liabilities at amortised cost, category [member]
Disclosure of information about structured entities [Line Items]
Financial liabilities	181	169
Securities [member] \| NHA MBS US Agency MBS And CMO [member]
Disclosure of information about structured entities [Line Items]
Associated liabilities	27,568	15,223
Securities [member] \| BMO managed funds [member]
Disclosure of information about structured entities [Line Items]
Assets recognised	1,196	848
Securities [member] \| BMO managed funds [member] \| Fair Value Through Profit Or Loss [Member]
Disclosure of information about structured entities [Line Items]
Assets recognised	278	250
Securities [member] \| BMO managed funds [member] \| Trading securities [member]
Disclosure of information about structured entities [Line Items]
Assets recognised	918	598
U.S. customer securitization vehicle [member]
Disclosure of information about structured entities [Line Items]
Sale of MBS to securitization vehicles	67,264	31,832
Canadian customer securitization vehicles [member]
Disclosure of information about structured entities [Line Items]
Undrawn amount under liquidity facilities	19,679	19,296
Funding vehicle [member]
Disclosure of information about structured entities [Line Items]
Commercial papers issued	$ 15,394	$ 9,682

Amount of committed financial support that may be required for structured entities.

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- Definition

Line items represent concepts included in structured entities table.

+ References

No definition available.

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- Definition

Gain or loss on sale of mortgage backed securities.

+ References

No definition available.

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- Definition

Mortgage backed securities at fair value.

+ References

No definition available.

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- Definition

Proceeds from sale of commercial mortgaged backed securities.

+ References

No definition available.

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- Definition

Proceeds from sale of mortgage backed securities.

+ References

No definition available.

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- Definition

The amount of assets recognised in the entity's financial statements relating to its interests in structured entities. [Refer: Assets; Total for all unconsolidated structured entities [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2024-01-01
-Paragraph 29
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- Definition

The amount of commercial paper issued by the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-IssueDate 2024-01-01
-Paragraph 112
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- Definition

The fair value of financial liabilities associated with transferred financial assets that are not derecognised in their entirety. [Refer: Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2024-01-01
-Paragraph 42D
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- Definition

The fair value of transferred financial assets that are not derecognised in their entirety. [Refer: Financial assets]

+ References

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- Definition

The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to deliver a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Classes of financial instruments [domain]; Financial assets; Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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-IssueDate 2024-01-01
-Paragraph 25
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2024-en-r&anchor=para_25&doctype=Standard
-URIDate 2024-03-27

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