Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value of Company's Financial Assets Measured on Recurring Basis

The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated, which are comprised solely of available-for-sale marketable securities with remaining contractual maturities of one year or less (in thousands):

June 30, 2019	InputLevel	Amortized Cost			Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds	Level 1	$	8,658		$	—	$	—	$	8,658
U.S. commercial paper	Level 2		2,386			—		—		2,386
Total available-for-sale securities			11,044			—		—		11,044
Less amounts classified as cash equivalents			(8,658	)		—		—		(8,658	)
Amounts classified as marketable securities		$	2,386		$	—	$	—	$	2,386

December 31, 2018	Input Level	Amortized Cost			Gross Unrealized Gains		Gross Unrealized Losses		EstimatedFair Value
Money market funds	Level 1	$	10,845		$	—	$	—	$	10,845
Total available-for-sale securities			10,845			—		—		10,845
Less amounts classified as cash equivalents			(10,845	)		—		—		(10,845	)
Amounts classified as marketable securities		$	—		$	—	$	—	$	—