10. Income taxes (Details - Unrecognized tax benefits) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 142	$ 63
Additions based on tax positions of prior years	0	79
Reduction for tax positions of prior years	(47)	0
Unrecognized tax benefits, ending balance	$ 95	$ 142