INCOME TAXES - Components of Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowance for credit losses	$ 1,418	$ 581
Inventory costs capitalized for tax purposes	165	134
Inventory valuation reserves	271	253
Sales return reserves	158	134
Deductible expenses, primarily employee-benefit related	661	177
Accrued compensation	3,295	2,448
Operating lease liability	3,559	3,858
Other	1,475	1,503
Compensation under non-statutory stock option agreements	393	143
State tax loss carryforwards	1,079	1,091
Total gross deferred tax assets	12,474	10,322
Less: Valuation allowance	(942)	(992)
Net deferred tax assets	11,532	9,330
Deferred tax liabilities:
Goodwill and other intangibles	(13,625)	(13,287)
Property and equipment	(12,976)	(12,482)
Right-of-use assets	(3,366)	(3,647)
Prepaid expenses	(90)	(84)
Total gross deferred tax liabilities.	(30,057)	(29,500)
Net deferred tax liability	(18,525)	(20,170)
Noncurrent deferred tax liability	(18,525)	(20,170)
Net deferred tax liability	$ (18,525)	$ (20,170)