FAIR VALUE DISCLOSURES - Schedule of Short-Term Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 13,936	$ 21,939
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	6	23
Fair Value	$ 13,930	$ 21,916
Debt securities, available-for-sale, term	1 year	1 year
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 13,936	$ 21,939
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	6	23
Fair Value	$ 13,930	$ 21,916

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Period between issuance and maturity of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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