Investments (Tables)

6 Months Ended

Jun. 30, 2014

Investments

Summary of investments

The following is a summary of our investments as of June 30, 2014 and December 31, 2013 (in thousands):

	June 30, 2014
			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Corporate debt securities
Due in one year or less	$	41,237	$	68	$	(4	)	$	41,301
Due in one to three years	89,780		210		(17		)	89,973
U.S. treasury and government agency securities
Due in one year or less	18,848		31		—			18,879
Due in one to three years	32,717		51		(5		)	32,763
Commercial paper
Due in one year or less	1,500		—		—			1,500
Total investments	$	184,082	$	360	$	(26	)	$	184,416

	December 31, 2013
			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Corporate debt securities
Due in one year or less	$	42,609	$	44	$	(4	)	$	42,649
Due in one to three years	91,443		137		(106		)	91,474
U.S. treasury and government agency securities
Due in one year or less	18,526		19		—			18,545
Due in one to three years	34,123		37		(25		)	34,135
Total investments	$	186,701	$	237	$	(135	)	$	186,803