FAIR VALUE DISCLOSURES (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of financial instruments measured at fair value on recurring basis

Financial instruments measured at fair value on a recurring basis as of December 31, 2019 and 2018 are as follows (in thousands):

	December 31, 2019						Total
	Fair value measurements using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market funds	$	63,351	$	—	$	—	$	63,351
U.S. Treasury securities	—		3,019		—		3,019
Total assets at fair value (1)	$	63,351	$	3,019	$	—	$	66,370

	December 31, 2018						Total
	Fair value measurements using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market funds	$	81,425	$	—	$	—	$	81,425
U.S. Treasury securities	—		13,930		—		13,930
Total assets at fair value (1)	$	81,425	$	13,930	$	—	$	95,355

(1) The above tables exclude $23.1 million and $29.6 million of cash held in banks as of December 31, 2019 and 2018, respectively.

Schedule of short-term investments

Short-term investments as of December 31, 2019 and 2018 consisted of the following (in thousands):

	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
U.S. Treasury securities	$	3,018	$	1	$	—	$	3,019
Total	$	3,018	$	1	$	—	$	3,019

	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. Treasury securities	$	13,936	$	—	$	(6	)	$	13,930
Total	$	13,936	$	—	$	(6	)	$	13,930