Schedule of Fair Value of Financial Instruments (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	$ 14,328,000	$ 1,639,000
Marketable equity securities	214,000
Fair Value, Inputs, Level 1 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	214,000
Marketable equity securities	214,000
Fair Value, Inputs, Level 2 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	14,114,000	1,639,000
Marketable equity securities
Fair Value, Inputs, Level 3 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities
Marketable equity securities
U.S. Government Obligations [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	323,000	1,014,000
U.S. Government Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities
U.S. Government Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	323,000	1,014,000
U.S. Government Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities
Corporate Obligations [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	13,791,000	625,000
Corporate Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities
Corporate Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities	13,791,000	625,000
Corporate Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Fair value of marketable debt securities