Receivables From, Payables To, and Deposits With Broker-Dealers and Clearing Organizations (Schedule of Receivable) (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Receivables from and deposits with broker-dealers and clearing organizations
DTCC / OCC / NSCC	$ 13,844,000	$ 17,841,000
Goldman Sachs	2,729,000	2,430,000
Pershing Capital	1,104,000	1,266,000
NFS	1,064,000	1,061,000
Securities fail-to-deliver	347,000	379,000
Globalshares	30,000	46,000
Total Receivables from and deposits with broker-dealers and clearing organizations	19,118,000	23,023,000
Payables to broker-dealers and clearing organizations
Securities fail-to-receive	6,789,000	1,810,000
Payables to broker dealers	45,000
Total Payables to broker-dealers and clearing organizations	$ 6,834,000	$ 1,810,000