Receivables From, Payables To, and Deposits With Broker-Dealers and Clearing Organizations (Schedule of Receivable) (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Receivables from and deposits with broker-dealers and clearing organizations
DTCC / OCC / NSCC	$ 11,030,000	$ 17,841,000
Goldman Sachs	2,496,000	2,430,000
Pershing Capital	1,178,000	1,266,000
NFS	1,006,000	1,061,000
Securities fail-to-deliver	128,000	379,000
Globalshares	21,000	46,000
Other receivables	18,000
Total Receivables from and deposits with broker-dealers and clearing organizations	15,877,000	23,023,000
Payables to broker-dealers and clearing organizations
Securities fail-to-receive	3,093,000	1,810,000
Payables to broker dealers	39,000
Total Payables to broker-dealers and clearing organizations	$ 3,132,000	$ 1,810,000