Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables represent the fair value hierarchy for those assets and liabilities that the Company measures at fair value on a recurring basis (in thousands):

	Fair Value Measurements at September 30, 2018 Using:
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds	$	5,028	$	5,028	$	—	$	—
Short-term investments - commercial paper		45,064		—		45,064		—
Short-term investments - corporate notes		18,126		—		18,126		—
Short-term investments - U.S. government bonds		32,141		—		32,141		—
Investment		399		399		—		—
Total assets	$	100,758	$	5,427	$	95,331	$	—

	Fair Value Measurements at December 31, 2017 Using:
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds	$	13,804	$	13,804	$	—	$	—
Short-term investments - commercial paper		14,982		—		14,982		—
Short-term investments - corporate notes		2,824		—		2,824		—
Short-term investments - U.S. government bonds		5,006		—		5,006		—
Investment		328		328		—		—
Total assets	$	36,944	$	14,132	$	22,812	$	—