Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

Summary of Assets Measured at Fair Value on Recurring Basis

The following table summarizes assets measured at fair value on a recurring basis at June 30, 2019 (in thousands):

			Active		Observable		Unobservable
	June 30,		Markets		Inputs		Inputs
Description	2019		(Level 1)		(Level 2)		(Level 3)
Cash	$	115	$	115	$	—	$	—
Money market funds (included in    cash and cash equivalents)		21,256		21,256		—		—
U.S. treasury securities (included in    marketable securities)		111,425		111,425		—		—
Total	$	132,796	$	132,796	$	—	$	—

The following table summarizes assets measured at fair value on a recurring basis at December 31, 2018 (in thousands):

			Active		Observable		Unobservable
	December 31,		Markets		Inputs		Inputs
Description	2018		(Level 1)		(Level 2)		(Level 3)
Money market funds (included in    cash and cash equivalents)	$	6,804	$	6,804	$	—	$	—
U.S. treasury securities (included in    cash and cash equivalents)		238		238		—		—
U.S. treasury securities (included in    marketable securities)		100,986		100,986		—		—
Total	$	108,028	$	108,028	$	—	$	—