Line of Credit (Narrative) (Details) - USD ($)		3 Months Ended	9 Months Ended
	Dec. 21, 2016	Sep. 30, 2018	Sep. 30, 2018
Line of Credit Facility [Line Items]
Outstanding amount on credit facility		$ 0	$ 0
Interest paid, capitalized or accrued		30,000	72,000
Amortization of debt issuance costs		20,000	$ 41,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Borrowing capacity description			provides for up to a maximum amount of $5 million based on a borrowing base equivalent of 85% of eligible accounts receivable plus the lesser of $2 million or 50% of eligible inventory
Maximum borrowing capacity	$ 5,000,000
Borrowing base equivalent of eligible accounts receivable, percentage	85.00%
Minimum interest rate	6.50%
Monthly interest payment	$ 2,000
Monthly administrative fee	$ 1,000
Annual facility fee on maximum amount borrowable	1.00%
Automatic renewal date	Dec. 31, 2019
Automatic renewal term	1 year
Debt issuance costs	$ 228,000
Minimum net worth required		13,000,000	$ 13,000,000
Minimum working capital required		4,000,000	4,000,000
Remaining borrowing capacity		$ 4,900,000	$ 4,900,000
Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Borrowing base equivalent of eligible inventory	$ 2,000,000
Borrowing base equivalent of eligible inventory, percentage	50.00%
Revolving Credit Facility [Member] | Prime Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.00%