Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured at Fair Value on Recurring Basis

The following tables summarize the Company’s financial assets measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017.

Fair value measurement as of September 30, 2018:

Financial assets			Quoted prices in		Significant other		Significant
			active markets for		observable		unobservable
			identical assets		inputs		inputs
Type of Instrument	Total		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents:
Money market fund and checking accounts	$	96,729	$	96,729	$	—	$	—
Available-for-sale marketable securities:
Money market funds		51,455		—		51,455		—
U.S. Treasury securities		2,996		—		2,996		—
U.S. government agency obligations		2,592		—		2,592		—
Corporate bonds		10,929		—		10,929		—
Commercial paper		41,376		—		41,376		—
Restricted cash:
Commercial money market account		769		769		—		—
Total financial assets	$	206,846	$	97,498	$	109,348	$	—

Fair value measurement as of December 31, 2017:

Financial assets			Quoted prices in		Significant other		Significant
			active markets for		observable		unobservable
			identical assets		inputs		inputs
Type of Instrument	Total		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents:
Money market fund and checking accounts	$	9,388	$	9,388	$	—	$	—
Available-for-sale marketable securities:
Money market fund		39,951		—		39,951		—
U.S. government agency obligations		7,794		—		7,794		—
Corporate bonds		15,907		—		15,907		—
Commercial paper		19,529		—		19,529		—
Restricted cash:
Commercial money market account		769		769		—		—
Total financial assets	$	93,338	$	10,157	$	83,181	$	—