Goodwill and Intangible Assets, Net (Schedule of Information Related to Intangible Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Purchase Price	$ 1,057,000
Amortization	213,000	$ 35,000
Total Intangible assets	$ 809,000	1,022,000	[1]
Customer Relationships [Member] | Weeden Prime Services LLC [Member]
Finite-Lived Intangible Assets [Line Items]
Date acquired	Nov. 30, 2019
Original useful life	6 years
Remaining useful life	4 years 10 months 25 days
Purchase Price	$ 987,000
Amortization	155,000	23,000
Total Intangible assets	$ 809,000	964,000
Trade Names [Member] | Weeden Prime Services LLC [Member]
Finite-Lived Intangible Assets [Line Items]
Date acquired	Nov. 30, 2019
Original useful life	6 months
Purchase Price	$ 70,000
Amortization	58,000	12,000
Total Intangible assets		$ 58,000

[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.