Receivables (Installment Recevables) (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Non-Impaired Financing Receivable, Related Allowance	$ 0	$ 0
Installment Receivables, Current	1,159,000	1,192,000
Installment Receivables, Long-Term	1,084,000	1,257,000
Total Installment Receivables	2,243,000	2,449,000
Unearned Interest	17,000	22,000
Unearned Interest - Noncurrent	0	0
Total Unearned Interest	(4,933,000)	(3,173,000)
Unearned Interest	17,000	22,000
Installment Receivables Net of Unearned Interest Current	1,142,000	1,170,000
Installment Receivables Net of Unearned Interest Noncurrent	1,084,000	1,257,000
Installment Receivables, Net of Unearned Interest	2,226,000	2,427,000
Allowance for doubtful accounts, current	(547,000)	(434,000)
Allowance for doubtful accounts, long-term	(986,000)	(1,080,000)
Allowance for doubtful accounts	(1,533,000)	(1,514,000)	$ (1,542,000)
Installment receivables, net	595,000	736,000
Installment receivables, net, long-term	98,000	177,000
Installment receivables, net	$ 693,000	$ 913,000