Short-term Investments (Tables)

9 Months Ended

Sep. 30, 2014

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 security as of September 30, 2014	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. government-related debt securities	$	1,518	$	1	$	—		$	1,519
Corporate debt securities		43,877		7		(27	)		43,857
Asset-backed securities		3,300		—		(2	)		3,298
Total available-for-sale securities	$	48,695	$	8	$	(29	)	$	48,674

Type of security as of December 31, 2013	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. government-related debt securities	$	1,565	$	1	$	—		$	1,566
Corporate debt securities		31,128		24		(3	)		31,149
Total available-for-sale securities	$	32,693	$	25	$	(3	)	$	32,715

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):

Contractual maturity	September 30, 2014		December 31, 2013
Maturing in one year or less	$	42,872	$	26,725
Maturing in one to three years		5,802		5,990
Total available-for-sale securities	$	48,674	$	32,715