Short-term Investments

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Short-term Investments

Short-term Investments

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

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

The Company has both the intent and ability to sell its available-for-sale investments maturing greater than one year within 12 months from the balance sheet date and, accordingly, has classified these securities as current in the condensed consolidated balance sheet.

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	)

The Company invests in securities that are rated investment grade or better. The unrealized losses on investments as of March 31, 2016 and December 31, 2015 were primarily caused by interest rate increases.

The Company reviews the individual securities in its portfolio to determine whether a decline in a security’s fair value below the amortized cost basis is other-than-temporary. The Company determined that as of March 31, 2016, there were no investments in its portfolio that were other-than-temporarily impaired.