Marketable Securities

Available-for-sale marketable securities and cash and cash equivalents as of September 30, 2017 and December 31, 2016 consist of the following (in thousands):



	September 30, 2017
	Amortized Cost Value		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	110,853	$	—	$	—	$	110,853
Money market funds	315,110		—		—		315,110
Domestic corporate debt securities	7,000		—		—		7,000
Domestic corporate commercial paper	13,975		—		—		13,975
Total	$	446,938	$	—	$	—	$	446,938

Marketable securities:
Domestic corporate debt securities	$	11,655	$	—	$	—	$	11,655
Domestic corporate commercial paper	9,487		2		—		9,489
Total	$	21,142	$	2	$	—	$	21,144



	December 31, 2016
	Amortized Cost Value		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash and cash equivalents:
Cash	$	77,443	$	—	$	—		$	77,443
Money market funds	173,631		—		—			173,631
Domestic corporate commercial paper	5,487		—		—			5,487
Domestic corporate debt securities	2,006		—		—			2,006
Total	$	258,567	$	—	$	—		$	258,567

Marketable securities:
Domestic corporate debt securities	$	19,317	$	—	$	(2	)	$	19,315
Domestic corporate commercial paper	31,852		78		—			31,930
Asset-backed securities	22,639		—		(4		)	22,635
Total	$	73,808	$	78	$	(6	)	$	73,880

There were no debt securities that had been in an unrealized loss position for more than 12 months as of September 30, 2017 or December 31, 2016, respectively. There were 3 debt securities in an unrealized loss position for less than 12 months at September 30, 2017 and there were 13 debt securities that had been in an unrealized loss position for less than 12 months at December 31, 2016. The aggregate unrealized loss on these securities as of September 30, 2017 and December 31, 2016 was less than $1 thousand and $6 thousand, respectively, and the fair value was $9.4 million and $35.7 million, respectively. The Company considered the decrease in market value for these securities to be primarily attributable to current economic conditions. As it was not more likely than not that the Company would be required to sell these securities before the recovery of their amortized cost basis, which may be at maturity, the Company did not consider these investments to be other-than-temporarily impaired as of September 30, 2017.

As of September 30, 2017, marketable securities consisted of investments that mature within one year.