Marketable Investments (Tables)

6 Months Ended

Jun. 30, 2018

Investments Debt And Equity Securities [Abstract]

Summary of Company's Marketable Investments

The following table summarizes the Company’s marketable investments (in thousands):

	As of June 30, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized			Market
	Cost		Gains		Losses			Value
Federal agency obligations	$	1,800	$	—	$	(2	)	$	1,798
Corporate obligations		48,548		—		(256	)		48,292
Total	$	50,348	$	—	$	(258	)	$	50,090

	As of December 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized			Market
	Cost		Gains		Losses			Value
Federal agency obligations	$	1,800	$	—	$	(7	)	$	1,793
Corporate obligations		52,721		—		(181	)		52,540
Total	$	54,521	$	—	$	(188	)	$	54,333

Summary of Maturity Periods of Marketable Investments

The following table summarizes the maturity periods of the marketable investments in the Company’s portfolio as of June 30, 2018 (in thousands).

	FY 2018		FY 2019		FY2020		Total
Federal agency obligations	$	1,798	$	—	$	—	$	1,798
Corporate obligations		15,753		26,772	$	5,767		48,292
Total	$	17,551	$	26,772	$	5,767	$	50,090

Summary of Gross Unrealized Losses and Market Value of Available-for-Sale Securities with Unrealized Losses

The following table shows the gross unrealized losses and market value of the Company’s available-for-sale securities with unrealized losses that are not deemed to be other-than-temporary, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position (in thousands):

	As of  June 30, 2018
	Less Than 12 Months				12 Months or Greater
	Market		Unrealized		Market		Unrealized
	Value		Losses		Value		Losses
Federal agency obligations	$	—	$	—	$	1,798	$	2
Corporate obligations		40,117		217		8,175		39
Total	$	40,117	$	217	$	9,973	$	41

	As of December 31, 2017
	Less Than 12 Months				12 Months or Greater
	Market		Unrealized		Market		Unrealized
	Value		Losses		Value		Losses
Federal agency obligations	$	—	$	—	$	1,793	$	7
Corporate obligations		31,723		149		20,817		32
Total	$	31,723	$	149	$	22,610	$	39

Summary of Company's Fair Value Hierarchy for its Financial Assets

The following table represents the Company’s fair value hierarchy for its financial assets (cash equivalents and investments) measured at fair value on a recurring basis (in thousands):

	As of  June 30, 2018
	Level 1		Level 2		Level 3		Total
Money market funds (1)	$	5,253	$	—	$	—	$	5,253
Federal agency obligations		—		1,798		—		1,798
Corporate obligations		—		48,292		—		48,292
Total	$	5,253	$	50,090	$	—	$	55,343

	As of December 31, 2017
	Level 1		Level 2		Level 3		Total
Money market funds (1)	$	492	$	—	$	—	$	492
Federal agency obligations		—		1,793		—	$	1,793
Corporate obligations		—		52,540		—		52,540
Total	$	492	$	54,333	$	—	$	54,825

(1) Included in cash and cash equivalents.