Marketable Securities

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

Marketable securities consisted of the following as of December 31, 2017 and 2016:

December 31, 2017	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Money market mutual funds	$	7,318	$	—	$	—		$	7,318
United States treasuries	1,002		—		(1		)	1,001
Total marketable securities designated as available-for-sale	$	8,320	$	—	$	(1	)	$	8,319

December 31, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Money market mutual funds	$	21,848	$	—	$	—	$	21,848
Certificates of deposit	3,864		—		—		3,864
Total marketable securities designated as available-for-sale	$	25,712	$	—	$	—	$	25,712

The amortized costs and fair value of debt securities as of December 31, 2017 and 2016 are shown below by effective maturity. Effective maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties.

December 31, 2017	Amortized Cost		Fair Value
Due in less than one year	$	1,002	$	1,001
Due after one year and within two years	—		—
	$	1,002	$	1,001
December 31, 2016	Amortized Cost		Fair Value
Due in less than one year	$	3,864	$	3,864
Due after one year and within two years	—		—
	$	3,864	$	3,864

Interest income from cash equivalents and marketable securities was $107 and $94 for the years ended December 31, 2017 and 2016, respectively.