FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of December 31, 2018 (in thousands):

			Fair Value Measurements, Using
	Total carrying value as of December 31, 2018		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Cash equivalents	$	139,805	$	139,805	$	—	$	—
Short-term investments		304,323		304,323		—		—
Long-term investments		—		—		—		—

The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of December 31, 2017 (in thousands):

			Fair Value Measurements, Using
	Total carrying value as of December 31, 2017		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Cash equivalents	$	27,532	$	27,532	$	—	$	—
Short-term investments		287,446		287,446		—		—
Long-term investments		14,794		14,794		—		—