11. INCOME TAXES - provision for (benefit from) income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Total Income Tax Provision	$ 1,247	$ (283)	$ 473
Federal Income Tax Provision	2,619	2,393	1,891
State Income Tax Provision	633	999	783
Total Income Tax Provision	3,252	3,392	2,674
Current [Member]
Operating Loss Carryforwards [Line Items]
Federal Income Tax Provision	1,397	2,701	1,482
State Income Tax Provision	608	974	719
Total Income Tax Provision	2,005	3,675	2,201
Deferred [Member]
Operating Loss Carryforwards [Line Items]
Federal Income Tax Provision	1,222	(308)	409
State Income Tax Provision	25	25	64
Total Income Tax Provision	$ 1,247	$ (283)	$ 473