SECURITIES LENDING - Additional information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Securities Lending [Abstract]
Interest expense securities lending	$ 1,100	$ 2,094	$ 2,723	$ 4,781

Refers to the amount of interest expenses associate with securities lending incurred during the period.

No definition available.

Name:	rily_InterestExpenseSecuritiesLending
Namespace Prefix:	rily_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration