INCOME TAXES - Effective tax rate - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Effective income tax rate differs from the statutory rate
U.S. statutory rate (as a percent)	21.00%	21.00%	35.00%
State income taxes, net (as a percent)	0.50%	0.50%	1.60%
Exempt municipal bond interest (as a percent)	(0.10%)	(0.10%)	(0.10%)
Foreign tax rates (as a percent)	1.40%	2.10%	0.50%
Qualified domestic production activities deduction (as a percent)			(0.80%)
Tax credits receivable (as a percent)	0.50%		(1.40%)
Adjustment of deferred tax balances (as a percent)	0.20%	0.10%	(24.20%)
Reserve for uncertain tax benefits (as a percent)	0.40%	(1.00%)	(0.30%)
Worthless stock deduction (as a percent)			(3.80%)
Other, net (as a percent)	0.20%	(0.20%)	(1.90%)
Effective income tax rate (as a percent)	24.10%	22.40%	4.60%
Unrecognized tax benefits	$ 3,339	$ 4,342	$ 4,342	$ 3,678	$ 3,339
Tax Cuts and Jobs Act, Change in Tax Rate, Income Tax Expense (Benefit)			(20,318)
Portion of unrecognized tax benefits that, if recognized, would favorably affect annual effective income tax rate				2,012	1,765
Interest and penalties included in liability for uncertain tax positions				562	477
Reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits
Unrecognized tax benefits at the beginning of the period	3,339	4,342	4,746
Increases in tax positions for the current year	1,164	448	394
Reductions in tax positions for lapse of statute of limitations	(576)	(751)	(793)
Reductions in tax positions for settlements and payments	(249)
Decreases in prior period unrecognized tax benefits		(700)	(5)
Unrecognized tax benefits at the end of the period	$ 3,678	$ 3,339	$ 4,342
Canada
Effective income tax rate differs from the statutory rate
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2031				$ 617
Spain
Effective income tax rate differs from the statutory rate
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2026					282
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2027					60
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2028					179
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2029					102
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2030					310
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2031					412
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2032					311
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2033					125
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2034					434
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2035					548
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2036					797
Tax benefits of foreign subsidiary tax loss carry forwards expiring in 2037					$ 407