Marketable Securities

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

All of the Company's marketable securities were available-for-sale and were classified based on their maturities. Marketable securities with remaining maturities at the date of purchase of three months or less are classified as cash equivalents. Short term investments are securities that original maturity or remaining maturity is greater than three months and not more than twelve months. Long-term investments are securities that original maturity or remaining maturity is greater than twelve months.

The table below summarizes the marketable securities as of September 30, 2019 and December 31, 2018:



	September 30, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
	(in thousands)
Money market funds	$	8,956	$	—	$	—		$	8,956
Cash equivalents	8,956		—		—			8,956

U.S. treasury securities	74,881		41		(12		)	74,910
Corporate bonds	8,693		6		—			8,699
Short-term investments	83,574		47		(12		)	83,609

Corporate bonds	5,251		22		—			5,273
Long-term investments	5,251		22		—			5,273
Total marketable securities	$	97,781	$	69	$	(12	)	$	97,838



	December 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
	(in thousands)
U.S. treasury securities	$	1,000	$	—	$	—		$	1,000
Commercial paper	6,635		—		—			6,635
Money market funds	15,223		—		—			15,223
Cash equivalents	22,858		—		—			22,858

U.S. treasury securities	65,491		2		(4		)	65,489
Corporate bonds	19,708		15		(3		)	19,720
Commercial paper	11,894		—		—			11,894
Short-term investments	97,093		17		(7		)	97,103
Total marketable securities	$	119,951	$	17	$	(7	)	$	119,961

The maturities of the long-term investments outstanding as of September 30, 2019 range from 13 to 14 months. Unrealized gains and losses on marketable securities are recorded in accumulated other comprehensive loss.