Revenue Recognition (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Stock borrow / stock loan	$ 2,240,000	$ 771,000	$ 4,087,000	$ 1,215,000
Gross revenue from stock borrow/ Stock loan	7,021,000	2,008,000	11,851,000	3,671,000
Expenses from stock borrow/stock loan	4,781,000	1,237,000	7,764,000	2,456,000
Client expenses	103,000	$ 134,000	330,000	$ 352,000
Other receivables	34,000		34,000
Accounts payable and accrued liabilities	$ 225,000		$ 225,000