Cash Equivalents and Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Schedule of Estimated Fair Value of Cash Equivalents and Marketable Securities

The following tables summarize the estimated fair value of the Company’s cash equivalents and marketable securities and the gross unrealized gains and losses (in thousands):

	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Cash equivalents:
Money market funds	$	7,180	$	—	$	—		$	7,180
Reverse repurchase agreements		6,250		—		—			6,250
Commercial paper		5,977		—		(1	)		5,976
Total cash equivalents		19,407		—		(1	)		19,406
Marketable securities:
Commercial paper		47,964		—		(24	)		47,940
U.S. government securities		4,114		—		(2	)		4,112
Total marketable securities	$	52,078	$	—	$	(26	)	$	52,052

	December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Cash equivalents:
Money market funds	$	1,674	$	—	$	—		$	1,674
Reverse repurchase agreements		7,250		—		—			7,250
Total cash equivalents		8,924		—		—			8,924
Marketable securities:
U.S. treasury securities		1,502		—		(1	)		1,501
U.S. government securities		36,082		—		(101	)		35,981
Total marketable securities	$	37,584	$	—	$	(102	)	$	37,482

Summary of Contractual Maturities of Marketable Securities at Estimated Fair Value

The following table summarizes the contractual maturities of the Company's marketable securities at estimated fair value (in thousands):

	December 31,
	2018		2017
Due in one year or less	$	52,052	$	34,498
Due in 1 - 2 years		—		2,984
Total marketable securities	$	52,052	$	37,482