FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2017

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 June 30, 2017 and December 31, 2016 are classified based on the valuation technique in the table below:

	June 30, 2017
	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)		Total
	(In thousands)
Assets:
U.S. Treasury securities	$	—	$	28,863	$	—	$	28,863
Money market accounts	16,096		—		—		16,096
Total assets at fair value	$	16,096	$	28,863	$	—	$	44,959

	December 31, 2016
	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)		Total
	(In thousands)
Assets:
U.S. Treasury securities	$	—	$	32,907	$	—	$	32,907
Money market accounts	32,031		—		—		32,031
Total assets at fair value	$	32,031	$	32,907	$	—	$	64,938

Schedule of short-term investments

Short-term Investments

	June 30, 2017
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
	(In thousands)
U.S. Treasury securities	$	28,894	$	—	$	(31	)	$	28,863
Total	$	28,894	$	—	$	(31	)	$	28,863

	December 31, 2016
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
	(In thousands)
U.S. Treasury securities	$	32,914	$	—	$	(7	)	$	32,907
Total	$	32,914	$	—	$	(7	)	$	32,907