Short-term Investments (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2014	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. government-related debt securities	$	1,550	$	1	$	—		$	1,551
Corporate debt securities		55,278		26		(18	)		55,286
Total available-for-sale securities	$	56,828	$	27	$	(18	)	$	56,837

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	March 31, 2014		December 31, 2013
Maturing in one year or less	$	53,286	$	26,725
Maturing after one year through three years		3,551		5,990
Total available-for-sale securities	$	56,837	$	32,715