Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of marketable securities

The following is a summary of our marketable securities as of June 30, 2018 and December 31, 2017 (in thousands):

	June 30, 2018
			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Short-term marketable securities:*
Corporate debt securities	$	55,303	$	1	$	(197	)	$	55,107
Certificates of deposit	9,450		—		—			9,450
U.S. treasury and government agency securities	5,998		—		(43		)	5,955
Commercial paper	7,452		—		—			7,452
Total short-term marketable securities	$	78,203	$	1	$	(240	)	$	77,964
Long-term marketable securities:**
Corporate debt securities	$	55,079	$	5	$	(685	)	$	54,399
U.S. treasury and government agency securities	6,383		—		(74		)	6,309
Total long-term marketable securities	61,462		5		(759		)	60,708
Total marketable securities	$	139,665	$	6	$	(999	)	$	138,672

* 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.