Short-term Investments (Tables)

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments Available-for-Sale Securities

Short-term investments consisted of available-for-sale securities as follows (in thousands):

Type of securities as of March 31, 2016	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	21,736	$	5	$	(3	)	$	21,738
U.S. government-related debt securities	5,410		3		—			5,413
Total available-for-sale securities	$	27,146	$	8	$	(3	)	$	27,151

Type of securities as of December 31, 2015	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	26,116	$	—	$	(28	)	$	26,088
U.S. government-related debt securities	1,101		—		(1		)	1,100
Total available-for-sale securities	$	27,217	$	—	$	(29	)	$	27,188

Fair Values of Available-for-Sale Securities by Contractual Maturity

The fair values of available-for-sale securities by contractual maturity were as follows (in thousands):

	March 31, 2016		December 31, 2015
Maturing in one year or less	$	25,647	$	27,188
Maturing in one to three years	1,504		—
Total available-for-sale securities	$	27,151	$	27,188

Summary of Investments in Continuous Unrealized Loss Position

The following table summarizes investments that have been in a continuous unrealized loss position as of March 31, 2016 (in thousands):

	Less Than 12 Months					12 Months or Greater				Total
	Fair value		Gross unrealized losses			Fair value		Gross unrealized losses		Fair value		Gross unrealized losses
Corporate debt securities	$	11,602	$	(3	)	$	—	$	—	$	11,602	$	(3	)
U.S. government-related debt securities	—		—			—		—		—		—
Total	$	11,602	$	(3	)	$	—	$	—	$	11,602	$	(3	)