Receivables (Installment Recevables) (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Non-Impaired Financing Receivable, Related Allowance	$ 0	$ 0
Installment Receivables, Current	741,000	1,192,000
Installment Receivables, Long-Term	338,000	1,257,000
Total Installment Receivables	1,079,000	2,449,000
Unearned Interest	10,000	22,000
Unearned Interest - Noncurrent	0	0
Total Unearned Interest	(2,794,000)	(3,173,000)
Unearned Interest	10,000	22,000
Installment Receivables Net of Unearned Interest Current	731,000	1,170,000
Installment Receivables Net of Unearned Interest Noncurrent	338,000	1,257,000
Installment Receivables, Net of Unearned Interest	1,069,000	2,427,000
Allowance for doubtful accounts, current	(328,000)	(434,000)
Allowance for doubtful accounts, long-term	(287,000)	(1,080,000)
Allowance for doubtful accounts	(615,000)	(1,514,000)	$ (1,542,000)
Installment receivables, net	403,000	736,000
Installment receivables, net, long-term	51,000	177,000
Installment receivables, net	$ 454,000	$ 913,000