FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2016

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

Cash equivalents, restricted cash and marketable securities by security type at December 31, 2016 were as follows:

(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Included in cash and cash equivalents:
Money market funds	$	11,193	$	—	$	—		$	11,193


Restricted cash:
Certificate of deposit	$	268	$	—	$	—		$	268


Marketable securities:
Government-sponsored enterprise securities (due in less than one year)	$	5,000	$	—	$	(3	)	$	4,997
Government-sponsored enterprise securities (due in one to two years)		12,500		—		(42	)		12,458
Commercial paper (due in less than one year)		31,024		50		(5	)		31,069
Corporate notes (due in less than one year)		66,012		4		(47	)		65,969
Corporate notes (due in one to two years)		1,506		—		(10	)		1,496

	$	116,042	$	54	$	(107	)	$	115,989

Cash equivalents, restricted cash and marketable securities by security type at December 31, 2015 were as follows:

(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Included in cash and cash equivalents:
Money market funds	$	4,577	$	—	$	—		$	4,577
Government-sponsored enterprise securities		1,999		—		—			1,999
Commercial paper		7,599		—		—			7,599
Corporate notes		5,002		—		(1	)		5,001

	$	19,177	$	—	$	(1	)	$	19,176


Restricted cash:
Certificate of deposit	$	267	$	—	$	—		$	267


Marketable securities:
Government-sponsored enterprise securities (due in one to two years)	$	10,007	$	—	$	(57	)	$	9,950
Commercial paper (due in less than one year)		27,661		49		(2	)		27,708
Corporate notes (due in less than one year)		64,892		1		(77	)		64,816
Corporate notes (due in one to two years)		22,837		—		(126	)		22,711

	$	125,397	$	50	$	(262	)	$	125,185

Schedule of cash equivalents and marketable securities with unrealized losses

	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
As of December 31, 2016:
Government-sponsored enterprise securities (due in less than one year)	$	4,997	$	(3	)	$	—	$	—		$	4,997	$	(3	)
Government-sponsored enterprise securities (due in one to two years)		12,458		(42	)		—		—			12,458		(42	)
Commercial paper (due in less than one year)		8,365		(5	)		—		—			8,365		(5	)
Corporate notes (due in less than one year)		39,218		(37	)		6,944		(10	)		46,162		(47	)
Corporate notes (due in one to two years)		1,496		(10	)		—		—			1,496		(10	)

	$	66,534	$	(97	)	$	6,944	$	(10	)	$	73,478	$	(107	)


As of December 31, 2015:
Government-sponsored enterprise securities (due in one to two years)	$	9,950	$	(57	)	$	—	$	—		$	9,950	$	(57	)
Commercial paper (due in less than one year)		7,834		(2	)		—		—			7,834		(2	)
Corporate notes (due in less than one year)		61,006		(71	)		6,301		(7	)		67,307		(78	)
Corporate notes (due in one to two years)		22,711		(126	)		—		—			22,711		(126	)

	$	101,501	$	(256	)	$	6,301	$	(7	)	$	107,802	$	(263	)

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 December 31, 2016 and indicates the fair value category assigned.

	Fair Value Measurements at Reporting Date Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
Money market funds(1)	$	11,193	$	—	$	—	$	11,193
Government-sponsored enterprise securities(2)(3)		—		17,455		—		17,455
Commercial paper(2)		—		31,069		—		31,069
Corporate notes(2)(3)		—		67,465		—		67,465

Total	$	11,193	$	115,989	$	—	$	127,182

The following table presents information about our financial instruments that are measured at fair value on a recurring basis as of December 31, 2015 and indicates the fair value category assigned.

	Fair Value Measurements at Reporting Date Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
Money market funds(1)	$	4,577	$	—	$	—	$	4,577
Government-sponsored enterprise securities(1)(3)		—		11,949		—		11,949
Commercial paper(1)(2)		—		35,307		—		35,307
Corporate notes(1)(2)(3)		—		92,528		—		92,528

Total	$	4,577	$	139,784	$	—	$	144,361


(1)	Included in cash and cash equivalents on our balance sheets.
(2)	Included in current portion of marketable securities on our balance sheets.
(3)	Included in noncurrent portion of marketable securities on our balance sheets.