INCOME TAXES - Effective tax rate - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective income tax rate differs from the statutory rate
U.S. statutory rate (as a percent)	21.00%	21.00%	21.00%
State income taxes, net (as a percent)	3.70%	2.30%	2.40%
Foreign income tax rates (as a percent)	0.30%	1.00%	0.20%
Income tax credits and adjustments (as a percent)	(0.60%)	(0.80%)	(0.60%)
Adjustment of deferred tax balances (as a percent)	(0.20%)	(0.70%)	0.60%
Reserve for uncertain tax benefits (as a percent)	(0.20%)	0.30%
Other, net (as a percent)	(0.60%)	(0.40%)	0.20%
Effective income tax rate (as a percent)	23.40%	22.70%	23.80%
Unrecognized tax benefits	$ 2,313	$ 3,392	$ 3,133
Portion of unrecognized tax benefits that, if recognized, would favorably affect annual effective income tax rate	1,736	1,734
Interest and penalties included in liability for uncertain tax positions	463	355
Reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits
Unrecognized tax benefits at the beginning of the period	3,392	3,133	3,011
Increases in tax positions for the current year	510	393	700
Reductions in tax positions for lapse of statute of limitations	(1,589)	(134)	(578)
Unrecognized tax benefits at the end of the period	2,313	3,392	$ 3,133
Foreign Tax Authority
Effective income tax rate differs from the statutory rate
Foreign subsidiary valuation allowances for net operating loss carryforwards	5,012	4,650
State tax credit carryforwards valuation allowances	1,349	1,053
Reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits
Foreign subsidiary valuation allowances for net operating loss carryforwards	5,012	4,650
State tax credit carryforwards valuation allowances	$ 1,349	$ 1,053