Cash Equivalents and Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2013

Cash Equivalents and Marketable Securities

Schedule of marketable securities

Marketable securities are summarized as follows (in thousands):

					Gross			Gross
					Unrealized			Unrealized
			Gross		Losses			Losses
	Amortized		Unrealized		Less than			12 Months		Aggregate
Balance at June 30, 2013	Cost		Gains		12 Months			or Longer		Fair Value
Corporate debt securities	$	11,662	$	—	$	(22	)	$	—	$	11,640
Foreign government debt securities	3,609		—		(6		)	—		3,603
Total	$	15,271	$	—	$	(28	)	$	—	$	15,243

					Gross			Gross
					Unrealized			Unrealized
			Gross		Losses			Losses
	Amortized		Unrealized		Less than			12 Months		Aggregate
Balance at December 31, 2012	Cost		Gains		12 Months			or Longer		Fair Value
Corporate debt securities	$	110,540	$	13	$	(45	)	$	—	$	110,508
US government debt securities	59,811		7		(3		)	—		59,815
Foreign government debt securities	2,415		6		—			—		2,421
Total	$	172,766	$	26	$	(48	)	$	—	$	172,744

Schedule of contractual maturities of marketable securities

The following table summarizes the contractual maturities of marketable securities at June 30, 2013 (in thousands):

	Amortized		Aggregate
	Cost		Fair Value
Matures within one year	$	6,020	$	6,013
Matures within one to three years	9,251		9,230
Total	$	15,271	$	15,243