Fair value of financial instruments - Summary of Net Interest Income From Financial Instruments (Detail) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2026	Jul. 31, 2025	Jul. 31, 2026	Jul. 31, 2025
Disclosure of detailed information about financial instruments [line items]
Interest income	$ 26,585	$ 26,110	$ 77,711	$ 77,535
Interest expense	17,841	17,759	51,876	53,180
Net interest income	8,744	8,351	25,835	24,355
Interest and dividend income [member] \| Financial assets measured at fair value through profit or loss [member]
Disclosure of detailed information about financial instruments [line items]
Interest income	7,768	7,679	22,688	22,932
Interest and dividend income [member] \| Financial assets measured at fair value through other comprehensive income [member]
Disclosure of detailed information about financial instruments [line items]
Interest income	2,475	2,240	7,050	6,395
Interest and dividend income [member] \| Financial assets measured at amortized cost [member]
Disclosure of detailed information about financial instruments [line items]
Interest income	16,342	16,191	47,973	48,208
Interest expense [member] \| Financial liabilities measured at fair value through profit or loss [member]
Disclosure of detailed information about financial instruments [line items]
Interest expense	7,947	7,623	23,050	22,985
Interest expense [member] \| Financial liabilities measured at amortized cost [member]
Disclosure of detailed information about financial instruments [line items]
Interest expense	$ 9,894	$ 10,136	$ 28,826	$ 30,195