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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Fair Value Measurements (Details) - USD ($)	3 Months Ended		9 Months Ended
Fair Value Measurements (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Gains and losses on equity instruments
Net gains recognized during the period on equity investments	$ 54,000	$ 12,000	$ 4,000	$ 125,000
Less: net gains recognized during the period on equity investments sold during the period	14,000		37,000
Unrealized gains (losses) recognized during the period on equity investments still held at period end	40,000	$ 12,000	(33,000)	$ 125,000
Total
Fair Value Measurements
Equity investments	1,197,000		1,197,000		$ 1,182,000
Level 1
Fair Value Measurements
Equity investments	$ 1,197,000		$ 1,197,000		$ 1,182,000