Amount due from customers for fees and charges arising from transactions related to the entity's brokerage activities and operations.

No definition available.

Name:	sieb_ReceivablesFromCustomers1
Namespace Prefix:	sieb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Financial Instruments with Off-Balance Sheet Risk [Abstract]
Margin loans extended			$ 373.6		$ 338.1
Receivables from customers			74.9		$ 72.8
Unsettled customer transactions