Investments (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments in Fixed Income Securities

Our investments in fixed income securities as of December 31, 2016 and 2015 were as follows:

	As of December 31, 2016
	Amortized						Fair
(in thousands)	cost		Gains		Losses		Value
Corporate debt securities	$	10,740	$	—	$	(2)	$	10,738
Commercial paper		47,473		8		(2)		47,479
Total	$	58,213	$	8	$	(4)	$	58,217

	As of December 31, 2015
	Amortized						Fair
(in thousands)	cost		Gains		Losses		Value
Corporate debt securities	$	28,549	$	1	$	(30)	$	28,520
Commercial paper		24,187		1		(1)		24,187
Securities and obligations of U.S. government agencies		12,431		—		(5)		12,426
Total	$	65,167	$	2	$	(36)	$	65,133

Summary of the Balance Sheet Classification of Investments

	As of December 31,
(in thousands)	2016		2015
Cash equivalents	$	22,029	$	13,499
Short-term investments		36,184		49,574
Long-term investments		—		2,094
Total investments	$	58,213	$	65,167

Schedule of Held-to-Maturity Investments by Contractual Maturity

	As of December 31,
	2016				2015
	Gross				Gross
	Amortized		Fair		Amortized		Fair
(in thousands)	Cost		Value		Cost		Value
Due in one year or less	$	58,213	$	58,217	$	63,073	$	63,040
Due after one year through five years		—		—		2,094		2,093
Total	$	58,213	$	58,217	$	65,167	$	65,133