Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of available-for-sale marketable securities and cash and cash equivalents

Available-for-sale marketable securities and cash and cash equivalents as of September 30, 2018 and December 31, 2017 consist of the following (in thousands):

	September 30, 2018
	Amortized Cost Value		Gross  Unrealized  Gains		Gross  Unrealized  Losses			Fair Value
Cash and cash equivalents:
Cash	$	15,236	$	—	$	—		$	15,236
Money market funds	46,778		—		—			46,778
Total	$	62,014	$	—	$	—		$	62,014
Marketable securities:
Domestic corporate debt securities	$	155,346	$	—	$	(643	)	$	154,703
Agency bonds	59,981		—		(329		)	59,652
Total	$	215,327	$	—	$	(972	)	$	214,355

	December 31, 2017
	Amortized Cost Value		Gross  Unrealized  Gains		Gross  Unrealized  Losses			Fair Value
Cash and cash equivalents:
Cash	$	73,302	$	—	$	—		$	73,302
Money market funds	325		—		—			325
Domestic corporate commercial paper	44,937		—		—			44,937
Total	$	118,564	$	—	$	—		$	118,564
Marketable securities:
Domestic corporate debt securities	$	207,320	$	1	$	(235	)	$	207,086
Domestic corporate commercial paper	29,844		—		(7		)	29,837
Agency bonds	74,842		—		(73		)	74,769
Total	$	312,006	$	1	$	(315	)	$	311,692