INCOME TAXES - Tax Effects and Tax Cuts and Jobs Act (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of components of income before income taxes
Domestic	$ 17,188	$ 10,894	$ 8,076
Foreign	6,653	9,787	8,060
Income before income taxes	23,841	20,681	16,136
Current provision
Domestic	4,313	1,663	4,750
Foreign	2,618	3,169	2,566
Total current provision	6,931	4,832	7,316
Deferred provision
Domestic	199	675	925
Foreign	(311)	(751)	(141)
Total deferred provision	(112)	(76)	784
Provision for income taxes	$ 6,819	$ 4,756	$ 8,100
Differences in the provision for income taxes from the amount determined by applying the federal statutory rate
Tax provision, computed at statutory rate (as a percent)	21.00%	21.00%	35.00%
State tax, net of federal impact (as a percent)	4.50%	3.00%	3.60%
Change in valuation allowance (as a percent)	0.30%	2.80%	1.90%
Effect of foreign tax rate differences (as a percent)	1.50%	3.40%	(4.20%)
Permanent items, other (as a percent)	1.40%	0.80%	0.20%
Section 162(m) compensation	1.10%	0.10%	0.00%
R&D Credit (as a percent)	(2.50%)	(0.80%)	(2.20%)
Restricted stock awards (as a percent)	(0.10%)	(2.30%)	(2.60%)
Effect of Tax Cuts and Jobs Act (as a percent)	(0.40%)	(5.10%)	19.40%
Tax examinations	1.80%	0.00%	0.00%
Other (as a percent)	0.00%	0.10%	(0.90%)
Provision for income taxes (as a percent)	28.60%	23.00%	50.20%
Effective tax rate excluding adjustments related to Tax Cuts and Jobs Act, Tax rate
Recognized provisional amount included as a component of income tax expense from continuing operations			$ 3,133
Provision for income taxes		$ 2,898
Reduction to provision for income taxes		$ 235
Decreased in effective tax rate (as a percent)		1.1
Transition tax liability			3,140
Decrease in transition tax liability			$ 17
Transition tax liability period (in years)			8 years
Remaining transition tax obligation	$ 1,858
Provisional amount of deferred tax balance			$ (7)
Decrease in deferred tax balance			218
Noncurrent deferred tax assets:
Employee benefit plans	2,440	$ 1,983
Net operating loss and tax credit carryforwards	795	983
Allowances and other	1,675	1,507
Other	428	326
Total noncurrent deferred tax assets	5,338	4,799
Valuation allowance	(1,077)	(1,003)
Net noncurrent deferred tax assets:	4,261	3,796
Net noncurrent deferred tax liabilities:
Property and equipment	3,901	3,708
Goodwill and intangibles	2,885	3,188
Other	384	419
Total deferred tax liabilities	7,170	7,315
Net deferred tax asset/(deferred tax liability)	$ (2,909)	$ (3,519)
Foreign tax credits			900
Tax effect on net operating losses			$ 200