Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of marketable securities

The following is a summary of our marketable securities as of March 31, 2018 and December 31, 2017 (in thousands):

	March 31, 2018
			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Short-term marketable securities:*
Corporate debt securities	$	58,981	$	—	$	(215	)	$	58,766
Certificates of deposit	10,150		—		—			10,150
U.S. treasury and government agency securities	5,996		—		(57		)	5,939
Commercial paper	5,962		—		—			5,962
Total short-term marketable securities	$	81,089	$	—	$	(272	)	$	80,817
Long-term marketable securities:**
Corporate debt securities	$	52,408	$	1	$	(725	)	$	51,684
U.S. treasury and government agency securities	6,381		—		(62		)	6,319
Total long-term marketable securities	58,789		1		(787		)	58,003
Total marketable securities	$	139,878	$	1	$	(1,059	)	$	138,820

* Represents marketable securities with a remaining maturity of less than one year.

** Represents marketable securities with a remaining maturity of one to three years.

	December 31, 2017
			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Short-term marketable securities:*
Corporate debt securities	$	57,257	$	—	$	(68	)	57,189
Certificates of deposit	9,151		—		—			9,151
U.S. treasury and government agency securities	1,999		—		(13		)	1,986
Commercial paper	1,999		—		—			1,999
Total short-term marketable securities	$	70,406	$	—	$	(81	)	$	70,325
Long-term marketable securities:**
Corporate debt securities	$	59,282	$	1	$	(320	)	$	58,963
U.S. treasury and government agency securities	7,381		—		(76		)	7,305
Total long-term marketable securities	66,663		1		(396		)	66,268
Total marketable securities	$	137,069	$	1	$	(477	)	$	136,593

* Represents marketable securities with a remaining maturity of less than one year.

** Represents marketable securities with a remaining maturity of one to three years.