Acquisitions (Schedule of Allocation of Purchase Price) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	[1]
Purchase Price Allocation
Goodwill	$ 1,989,000	$ 1,989,000
Weeden Prime Services LLC [Member]
Purchase Price Allocation
Cash and cash equivalents	301,000
Cash segregated under federal regulations	152,000
Receivables from broker-dealers and clearing organizations	4,616,000
Furniture, equipment, and leasehold improvements, net	41,000
Software, net	51,000
Intangible assets, net	1,057,000
Lease right-of-use assets	214,000
Prepaid expenses and other assets	271,000
Total Assets acquired	6,703,000
Accounts payable and accrued liabilities	1,353,000
Lease liabilities	214,000
Total Liabilities assumed	1,567,000
Net Assets acquired	5,136,000
Goodwill	1,989,000
Purchase price	$ 7,125,000

[1] Statement of financial condition as of December 31, 2019 represents the pro forma combination of Siebert and StockCross balances. See "Note 3 - Acquisitions" for additional detail.