SIGNIFICANT ACCOUNTING POLICIES - Exclusive Option Agreement (Details)	12 Months Ended
Dec. 31, 2019 USD ($) $ / shares
SIGNIFICANT ACCOUNTING POLICIES
Purchase price for equity interests in Shenzhen Futu under exclusive option agreement \| $ / shares	$ 1.00
Threshold of Shenzhen Futu disposes of Shenzhen Futu's material assets without prior written consent of Shen Si \| $	$ 500,000

Amount represents the material contract of value of assets under exclusive option agreement.

No definition available.

Name:	futu_MaterialContractOfValueOfAssetsUnderExclusiveOptionAgreement
Namespace Prefix:	futu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant