Income taxes (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income (loss) before income taxes	$ 2,341	$ 646	$ (1,037)
Computed "expected" tax expense (benefit)	796	220	(352)
Valuation allowance change	(11,997)	(277)	334
State taxes, net of fed	(39)	0	44
Cash surrender value of life insurance	(63)	(62)	(62)
Other	131	119	36
Provision (benefit) for income taxes	$ (11,172)	$ 0	$ 0