FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Transfers Between Level 1 and Level 2 (Details) - HKD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
FINANCIAL ASSETS AND FINANCIAL LIABILITIES
Fair value asset transferred from level 1 to level 2	$ 0	$ 0

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

No definition available.

Name:	futu_FairValueAssetsLevel1ToLevel2TransfersAmount1
Namespace Prefix:	futu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant