INCOME TAXES - Components of deferred income tax liabilities and assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2015	Dec. 31, 2017
Deferred income tax liabilities:
Book over tax basis of intangible and fixed assets	$ (94,649)		$ (113,844)
Unremitted foreign earnings	(4,735)
Other, net	(4,078)		(2,684)
Total deferred income tax liabilities	(103,462)		(116,528)
Deferred income tax assets:
Allowance for doubtful accounts and receivable adjustments	1,676		1,401
Inventory	1,629		1,807
Accrued liabilities	9,260		9,586
Net operating loss and tax credit carryforwards	184,381		196,633
Tax deductible goodwill	3,147		3,862
Disallowed Interest Deduction	27,005
Other, net	16,841		15,518
Total deferred income tax assets	243,939		228,807
Valuation allowance	(135,465)		(108,622)
Total net deferred income tax assets	5,012		$ 3,657
Increase (decrease) in valuation allowance	26,800
Federal
Deferred income tax assets:
Valuation allowance related to disallowed interest deduction	21,800
Valuation allowance related to limitation of utilization of NOL carryforwards	76,200
Increase (decrease) in valuation allowance		$ (3,500)
State
Deferred income tax assets:
Valuation allowance related to disallowed interest deduction	2,600
Valuation allowance related to limitation of utilization of NOL carryforwards	8,700
Foreign.
Deferred income tax assets:
Valuation allowance related to disallowed interest deduction	$ 26,200