Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Investments, Cost [Abstract]
Margin loans extended	$ 354.0	$ 365.4
Receivables from customers	$ 51.9	$ 52.1

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