Income taxes (Details - Deferred tax assets) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax liabilities attributable to:
Accumulated depreciation and amortization	$ (3,401)	$ (3,281)
Unrealized gains	(473)	(467)
Total deferred tax liabilities	(3,874)	(3,748)
Deferred tax assets attributable to:
Net operating losses	6	6
Accrued compensation	170	149
Incentive compensation	164	168
Inventory	324	323
Allowances for doubtful accounts and discounts	5	109
Deferred revenue	10	15
Other	(6)	34
Total net deferred tax assets	673	804
Net deferred tax liabilities	$ (3,201)	$ (2,944)