Marketable Securities

3 Months Ended

Mar. 31, 2019

Investments Debt And Equity Securities [Abstract]

Marketable Securities

4. Marketable Securities

Marketable securities, which are classified as available-for-sale, consisted of the following as of March 31, 2019 (in thousands):

	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	29,239	$	—	$	—		$	29,239
Short-term marketable securities:
U.S. and foreign commercial paper	$	16,607	$	10	$	(1	)	$	16,616
U.S. and foreign corporate debt securities		16,404		5		(1	)		16,408
U.S. government debt securities		65,711		14		(4	)		65,721
U.S. treasuries		17,208		1		(5	)		17,204
Total short-term marketable securities		115,930		30		(11	)		115,949
Total marketable securities	$	145,169	$	30	$	(11	)	$	145,188

Marketable securities, which are classified as available-for-sale, consisted of the following as of December 31, 2018 (in thousands):

	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	14,131	$	—	$	—		$	14,131
Short-term marketable securities:
U.S. and foreign commercial paper		10,638		—		(3	)		10,635
U.S. and foreign corporate debt securities		26,552		2		(21	)		26,533
Asset-backed securities		2,750		—		(2	)		2,748
U.S. government debt securities		81,755		1		(57	)		81,699
U.S. treasuries		34,136		1		(16	)		34,121
Total short-term marketable securities		155,831		4		(99	)		155,736
Total marketable securities	$	169,962	$	4	$	(99	)	$	169,867

There have been no significant realized gains or losses on available-for-sale securities for the periods presented. Available-for-sale debt securities that were in a continuous loss position but were not deemed to be other than temporarily impaired were immaterial at both March 31, 2019 and December 31, 2018.