INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	[1]	Sep. 30, 2018	Sep. 30, 2017
Income Tax Contingency [Line Items]
Income Tax Expense (Benefit)	$ (684)	$ 232		$ (281)	$ 417	[1]
Income tax provision due to U.S. federal and state income taxes and foreign income taxes				1,200	$ 400
Net discrete tax expense (benefit)				(1,500)
Unrecognized tax benefits	24,400			24,400
Unrecognized tax benefits that would not impact the effective tax rate	23,500			23,500
Unrecognized tax benefits increase	2,000
Earnings of foreign subsidiaries to be reinvested indefinitely	$ 3,300			$ 3,300
Federal and State Tax Jurisdictions
Income Tax Contingency [Line Items]
Open tax year				2003
Canada, Ireland, United Kingdom and Germany Tax Jurisdictions
Income Tax Contingency [Line Items]
Open tax year				2010

[1] As of January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Accordingly, the Company has recast certain amounts in the prior periods presented. See Note 1 below for additional discussion.