Equity Method Investments (Schedule of Supplemental Operations Information) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue	$ 28,593,000	$ 30,036,000
Net income / (loss)	3,607,000	11,962,000
StockCross [Member]
Revenue	14,823,000	13,340,000
Operating income / (loss)	(508,000)	(929,000)
Net income / (loss)	$ (420,000)	$ (691,000)