Income taxes (Details - Unrecognized tax benefits) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 95	$ 142
Additions based on tax positions of prior years	301	0
Reduction for tax positions of prior years	0	(47)
Unrecognized tax benefits, ending balance	$ 396	$ 95