FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of cash equivalents, restricted cash and marketable securities by security type

Cash equivalents, restricted cash and marketable securities by security type at June 30, 2019 were as follows:

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
(In thousands)	Cost		Gains		Losses			Fair Value
Included in cash and cash equivalents:
Money market funds	$	15,457	$	—	$	—		$	15,457

Restricted cash:
Certificate of deposit	$	270	$	—	$	—		$	270
Marketable securities:
Commercial paper (due in less than one year)	$	42,000	$	83	$	(1	)	$	42,082
Corporate notes (due in less than one year)		92,546		155		(5	)		92,696
Corporate notes (due in one to two years)		9,448		50		(1	)		9,497
	$	143,994	$	288	$	(7	)	$	144,275

Cash equivalents, restricted cash and marketable securities by security type at December 31, 2018 were as follows:

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
(In thousands)	Cost		Gains		Losses			Fair Value
Included in cash and cash equivalents:
Money market funds	$	7,003	$	—	$	—		$	7,003

Restricted cash:
Certificate of deposit	$	269	$	—	$	—		$	269
Marketable securities:
Commercial paper (due in less than one year)	$	57,594	$	22	$	(29	)	$	57,587
Corporate notes (due in less than one year)		95,238		7		(118	)		95,127
Corporate notes (due in one to two years)		18,647		—		(65	)		18,582
	$	171,479	$	29	$	(212	)	$	171,296

Schedule of cash equivalents and marketable securities with unrealized losses

Cash equivalents and marketable securities with unrealized losses that have been in a continuous unrealized loss position for less than 12 months and 12 months or longer at June 30, 2019 and December 31, 2018 were as follows:

	Less Than 12 Months					12 Months or Longer					Total
			Gross					Gross					Gross
	Estimated		Unrealized			Estimated		Unrealized			Estimated		Unrealized
(In thousands)	Fair Value		Losses			Fair Value		Losses			Fair Value		Losses
As of June 30, 2019:
Commercial paper (due in less than one year)	$	5,492	$	(1	)	$	—	$	—		$	5,492	$	(1	)
Corporate notes (due in less than one year)		11,318		(4	)		4,400		(1	)		15,718		(5	)
Corporate notes (due in one to two years)		1,053		(1	)		—		—			1,053		(1	)
	$	17,863	$	(6	)	$	4,400	$	(1	)	$	22,263	$	(7	)
As of December 31, 2018:
Commercial paper (due in less than one year)	$	22,628	$	(29	)	$	—	$	—		$	22,628	$	(29	)
Corporate notes (due in less than one year)		66,557		(82	)		14,221		(36	)		80,778		(118	)
Corporate notes (due in one to two years)		18,582		(65	)		—		—			18,582		(65	)
	$	107,767	$	(176	)	$	14,221	$	(36	)	$	121,988	$	(212	)

Schedule of financial instruments measured at fair value on recurring basis

The following table presents information about our financial instruments that are measured at fair value on a recurring basis as of June 30, 2019 and December 31, 2018 and indicates the fair value category assigned.

	Fair Value Measurements at Reporting Date Using
	Quoted Prices in				Significant
	Active Markets for		Significant Other		Unobservable
	Identical Assets		Observable Inputs		Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
As of June 30, 2019:
Money market funds⁽¹⁾	$	15,457	$	—	$	—	$	15,457
Commercial paper⁽²⁾		—		42,082		—		42,082
Corporate notes⁽²⁾⁽³⁾		—		102,193		—		102,193
Equity investment⁽⁴⁾		—		582		—		582
Total	$	15,457	$	144,857	$	—	$	160,314
As of December 31, 2018:
Money market funds⁽¹⁾	$	7,003	$	—	$	—	$	7,003
Commercial paper⁽²⁾		—		57,587		—		57,587
Corporate notes⁽²⁾⁽³⁾		—		113,709		—		113,709
Equity investment⁽⁴⁾		—		585		—		585
Total	$	7,003	$	171,881	$	—	$	178,884

(1)	Included in cash and cash equivalents on our condensed balance sheets.

(2)	Included in current portion of marketable securities on our condensed balance sheets.

(3)	Included in noncurrent portion of marketable securities on our condensed balance sheets.

(4)	Included in other assets on our condensed balance sheets. See further discussion below of this equity investment.