Investment Securities - Summary of Equity Investment Securities Designated as at Fair Value Through Other Comprehensive Income (Detail) - Investments in equity instruments designated at fair value through other comprehensive income [member] - CAD ($) $ in Millions	Jan. 31, 2026	Oct. 31, 2025
Disclosure of financial assets [line items]
Cost	$ 154	$ 178
Gross unrealized gains	224	221
Gross unrealized losses	1	1
Fair value	377	398
Common shares [member]
Disclosure of financial assets [line items]
Cost	154	178
Gross unrealized gains	224	221
Gross unrealized losses	1	1
Fair value	$ 377	$ 398