Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Financial Instruments with Off-Balance Sheet Risk [Abstract]
Margin loans extended	$ 338.1	$ 365.4
Receivables from customers	72.8	52.1
Unsettled customer transactions

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:	instant