9. Inccome taxes (Details - Reconciliation) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal income tax expense computed at the statutory rate	$ (274)	$ 1,917
State and local tax expense, net	1	320
U.S. domestic manufacturers' deduction & other permanent differences	111	113
Additions for tax positions of prior years	118	(202)
Change in tax rates	(378)	2
Change in tax estimate	(36)	8
Provision for income taxes	$ (458)	$ 2,158
Federal income tax expense computed at the statutory rate, percentage	34.00%	34.00%
State and local tax expense, net, percentage	(0.10%)	(5.70%)
U.S. domestic manufacturers' deduction & other permanent differences, percentage	(13.80%)	2.00%
Additions for tax positions of prior years, percentage	(14.60%)	(3.50%)
Change in tax rates, percentage	47.00%	0.00%
Change in tax estimate, percentage	4.50%	0.10%
Provision for income taxes, percentage	57.00%	38.30%