Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on Recurring Basis

Assets measured at fair value on a recurring basis are as follows (in thousands):

			Fair Value Measurements Using
			QuotedPricesin ActiveMarkets forIdentical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of September 30, 2017:
Assets:
Current:
Cash equivalents	$	17,907	$	17,907	$	—	$	—
Available-for-sale investments, short-term:
Asset-backed securities		7,402		—		7,402		—
Commercial paper		21,193		—		21,193		—
Corporate debt securities		21,594		—		21,594		—
United States treasury securities		10,427		10,427		—
Sub-total short-term investments		60,616		10,427		50,189		—
Total assets measured at fair value	$	78,523	$	28,334	$	50,189	$	—
As of December 31, 2016:
Assets:
Current:
Cash equivalents	$	29,251	$	29,251	$	—	$	—
Available-for-sale investments, short-term:
Commercial paper		7,843		—		7,843		—
Corporate debt securities		20,913		—		20,913		—
United States treasury securities		5,003		5,003		—		—
Sub-total short-term investments		33,759		5,003		28,756		—
Available-for-sale investments, long-term:
Asset-backed securities		4,002		—		4,002		—
Sub-total long-term investments		4,002		—		4,002		—
Total assets measured at fair value	$	67,012	$	34,254	$	32,758	$	—

Schedule of Available-for-sale Investments

As of September 30, 2017 and December 31, 2016 available-for-sale investments are detailed as follows (in thousands):

	September 30, 2017
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Market Value
Available-for-sale investments, short-term:
Asset-backed securities	$	7,403		—		(1	)	$	7,402
Commercial paper		21,193		—		—			21,193
Corporate debt securities		21,601		—		(7	)		21,594
United States treasury securities		10,433		—		(6	)		10,427
	$	60,630	$	—	$	(14	)	$	60,616

	December 31, 2016
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Market Value
Available-for-sale investments, short-term:
Commercial paper	$	7,843	$	—	$	—		$	7,843
Corporate debt securities		20,942		—		(29	)		20,913
United States Treasury securities		5,002		1		—			5,003
	$	33,787	$	1	$	(29	)	$	33,759
Available-for-sale investments, long-term:
Asset-backed securities	$	4,001	$	1	$	—		$	4,002
	$	4,001	$	1	$	—		$	4,002