The following table presents additional information about marketable equity securities: (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Net Investment Income [Line Items]
Sales of marketable equity securities	$ (4,062,000)	$ (373,000)
Realized gains on marketable equity securities	1,924,000
Unrealized losses on marketable equity securities	(1,327,000)	919,000
Purchases of marketable equity securities	2,500,000
Realized losses on marketable equity securities	21,187,000	75,000
Equity Securities [Member]
Net Investment Income [Line Items]
Balance at January 1, 2021	2,563,000	640,000
Purchases of marketable equity securities in operations	385,235,000	1,425,000
Sales of marketable equity securities	(4,062,000)	(373,000)
Realized gains on marketable equity securities	27,377,000	75,000
Unrealized losses on marketable equity securities	(14,127,000)	796,000
Purchases of marketable equity securities	2,765,000
Conversion of debt securities to marketable securities	2,656,000
Sales of marketable equity securities in operations	(355,837,000)
Realized losses on marketable equity securities	(6,190,000)
Balance at December 31, 2021	$ 40,380,000	$ 2,563,000