SHORT TERM INVESTMENTS, PREPAID EXPENSES AND OTHER CURRENT ASSETS - Schedule of Prepaid Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Prepaid income tax	$ 1,425	$ 5,429
Other prepaid expenses and other current assets	614	1,151
Total	$ 2,039	$ 6,580

Amount of asset related to consideration paid in advance for income and other taxes that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant