Available-for-Sale Marketable Securities

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Available-for-Sale Marketable Securities

As of March 31, 2018 and December 31, 2017, the Company’s available-for-sale marketable securities consisted of U.S. government and agency securities, commercial paper and corporate bonds.

The following tables summarize the Company’s available-for-sale marketable securities by major type of security as of March 31, 2018 and December 31, 2017 (in thousands):



	March 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government and agency securities	$	22,854	$	—	$	(13	)	$	22,841
Commercial paper	1,998		—		—			1,998
Total available-for-sale marketable securities	$	24,852	$	—	$	(13	)	$	24,839



	December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government and agency securities	$	12,798	$	—	$	(10	)	$	12,788
Corporate bonds	13,158		—		(6		)	13,152
Total available-for-sale marketable securities	$	25,956	$	—	$	(16	)	$	25,940

All available-for-sale marketable securities are classified in the Company’s consolidated balance sheets as short-term deposits and investments.

The Company classifies its marketable debt securities based on their contractual maturity dates. As of March 31, 2018, the Company’s marketable debt securities mature at various dates through August 2018. The fair values and amortized cost of marketable debt securities by contractual maturity were as follows (in thousands):



	March 31, 2018				December 31, 2017
	Fair Value		Amortized Cost		Fair Value		Amortized Cost
Less than one year	$	24,839	$	24,852	$	25,940	$	25,956

As of March 31, 2018, the Company held a total of 10 U.S. government and agency security positions, all of which were in an unrealized loss position, none of which had been in an unrealized loss position for 12 months or greater. The aggregate fair value of U.S. government and agency security investments in an unrealized loss position is $22.8 million. During the three months ended March 31, 2018, the Company recognized an unrealized loss of less than $0.1 million through net loss relating to changes in the fair value of its investment securities.

Based on the Company’s review of these securities, the Company believes that the cost basis is recoverable and it had no other-than-temporary impairments on these securities as of March 31, 2018. The Company does not intend to sell these debt securities and the Company believes it is not more-likely-than-not that it will be required to sell these securities before the recovery of their amortized cost basis, which may be at maturity.