INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Loss carryforwards	$ 55,900
Additional income tax expense - German tax audit settlement	$ 0	$ (338)	$ 812
Federal statutory income tax rate	35.00%	35.00%	35.00%
Deferred tax assets valuation allowance	$ 9,357	$ 3,032
Change in valuation allowances	6,642	3,737	$ 73
Change in federal tax laws for 2012, tax benefit			908
Decrease in additional paid-in-capital for tax impact of stock-based compensation	303		907
Increase in additional paid-in capital for tax impact of stock-based compensation		106
Income considered to be permanently reinvested in non-U.S. subsidiaries	30,726	37,772	37,795
Unrecognized tax benefits	0	0
Accrual for interest and penalties related to uncertain tax positions	0	$ 0
German Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Additional income tax expense - German tax audit settlement			$ 812
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards	46,690
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards	$ 9,210