Equity Method Investments (Schedule of Supplemental Operations Information) (Details) - USD ($)	3 Months Ended				6 Months Ended		9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue	$ 7,144,000		$ 7,884,000				$ 20,634,000	$ 23,549,000
Net income	1,104,000	$ 1,006,000	$ 3,119,000	$ 1,693,000	$ 992,000	$ 1,800,000	3,102,000	$ 6,611,000
StockCross [Member]
Revenue	3,757,000						11,552,000
Operating income	189,000						747,000
Net income	$ 189,000						$ 534,000