Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Assets measured at fair value on a recurring basis

The following table presents the financial instruments measured at fair value on a recurring basis and the valuation approach applied to each class of financial instruments as of June 30, 2018 and December 31, 2017 (in thousands):

	June 30, 2018
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Cash equivalents
Money market funds	$	10,134	$	—	$	—	$	10,134
Corporate notes and bonds	—		999		—		999
Marketable securities
Corporate notes and bonds	—		13,801		—		13,801
U.S. government and agency securities	—		3,483		—		3,483
Commercial paper	—		9,074		—		9,074
Total	$	10,134	$	27,357	$	—	$	37,491
	December 31, 2017
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Cash equivalents
Money market funds	$	6,362	$	—	$	—	$	6,362
Corporate notes and bonds	—		1,498		—		1,498
Marketable securities
Corporate notes and bonds	—		26,278		—		26,278
U.S. government and agency securities	—		11,976		—		11,976
Commercial paper	—		6,982		—		6,982
Total	$	6,362	$	46,734	$	—	$	53,096