Condensed Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities:
Net income	$ 3,000,000	$ 3,625,000
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation	451,000	432,000
Depreciation and amortization	602,000	525,000
Gain (loss) on marketable securities	(231,000)	50,000
Equity in income of unconsolidated affiliate	(359,000)	(587,000)
Operating lease expense, net of accretion	704,000
Deferred income taxes	83,000	159,000
Changes in assets and liabilities:
Accounts receivable, net	1,367,000	(338,000)
Accounts receivable, related party	(341,000)	(22,000)
Inventories	(1,425,000)	371,000
Prepaid expenses	412,000	(1,334,000)
Accounts payable and accrued liabilities	(500,000)	(881,000)
Lease liabilities	(662,000)
Net cash provided by operating activities	3,101,000	2,000,000
Cash Flows From Investing Activities:
Purchase of property and equipment	(1,296,000)	(606,000)
Proceeds from sales of marketable securities	154,000	36,000
Net cash used in investing activities	(1,142,000)	(570,000)
Cash Flows From Financing Activities:
Proceeds from exercise of stock options	130,000	394,000
Repurchase of common stock	(2,548,000)	(3,580,000)
Net cash used in financing activities	(2,418,000)	(3,186,000)
Decrease in cash	(459,000)	(1,756,000)
Cash and cash equivalents, beginning of the year	7,007,000	8,763,000
Cash and cash equivalents, end of the year	6,548,000	7,007,000
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 633,000	$ 908,000