ACCUMULATED OTHER COMPREHENSIVE INCOME - Summary (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Loss
Balance at beginning of period			$ 993,346
Other comprehensive (loss) income before reclassifications	$ 187	$ 3,578	(902)	$ 5,069
Amounts reclassified to earnings			(52)
Net current period other comprehensive (loss) income			(954)
Balance at end of period	1,102,762		1,102,762
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Loss
Balance at beginning of period	1,091	(230)	2,232	(1,721)
Balance at end of period	1,278	3,348	1,278	3,348
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	1,091	(230)	2,232	(1,721)
Other comprehensive (loss) income before reclassifications	190	3,578	(899)	5,069
Amounts reclassified to earnings			(52)
Net current period other comprehensive (loss) income			(951)
Balance at end of period	1,281	$ 3,348	1,281	$ 3,348
Unrealized Losses On Available-For-Sale Debt Securities
Accumulated Other Comprehensive Loss
Balance at beginning of period	0		0
Other comprehensive (loss) income before reclassifications	(3)		(3)
Amounts reclassified to earnings			0
Net current period other comprehensive (loss) income			(3)
Balance at end of period	$ (3)		$ (3)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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