Short-term Investments

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Short-term Investments

3. Short-term Investments

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

Type of security 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

Type of security as of December 31, 2014	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	47,345	$	2	$	(40	)	$	47,307
U.S. government-related debt securities		4,502		—		(4	)		4,498
Asset-backed securities		3,198		—		(1	)		3,197
Total available-for-sale securities	$	55,045	$	2	$	(45	)	$	55,002

The fair values of available-for-sale securities by contractual maturity at December 31 were as follows (in thousands):

	2015		2014
Maturing in one year or less	$	27,188	$	51,235
Maturing in one to three years		—		3,767
Total available-for-sale securities	$	27,188	$	55,002

The following table summarizes investments that have been in a continuous unrealized loss position as of December 31, 2015 (in thousands):

	Less Than 12 Months					More Than 12 Months					Total
	Fair value		Gross unrealized losses			Fair value		Gross unrealized losses			Fair value		Gross unrealized losses
Corporate debt securities	$	23,357	$	(24	)	$	2,730	$	(4	)	$	26,087	$	(28	)
U.S. government-related debt securities		1,100		(1	)		—		—			1,101		(1	)
Total	$	24,457	$	(25	)	$	2,730	$	(4	)	$	27,188	$	(29	)

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 December 31, 2015, there were no investments in its portfolio that were other-than-temporarily impaired.