Receivables from and Payable to Brokers, Dealers, and Clearing Organizations (Schedule of Amounts Receivable) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Receivables from clearing and other brokers
NFS	$ 1,664,000	$ 1,396,000
StockCross	310,000
Other receivables	31,000
Citibank	25,000
Total Receivables from clearing and other brokers	2,030,000	1,396,000
Receivable from related party
StockCross	1,000,000	283,000
Total Receivable from related party	1,000,000	283,000
Due to clearing brokers and related parties
NFS	58,000
StockCross	46,000	127,000
MSCO	29,000
Total Due to clearing brokers and related parties	$ 133,000	$ 127,000