Equity Method Investments (Schedule of Supplemental Operations Information) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 7,061,000	$ 7,488,000	$ 13,490,000	$ 15,665,000
Net income	992,000	$ 1,799,000	1,998,000	$ 3,492,000
StockCross [Member]
Revenue	3,781,000		7,795,000
Gross profit	273,000		558,000
Net income	$ 99,000		$ 345,000