Investments (Tables)

12 Months Ended

Dec. 31, 2013

Investments

Summary of investments

The following is a summary of our investments as of December 31, 2013 and 2012 (in thousands):

	December 31, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair 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

	December 31, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate debt securities
Due in one year or less	$	52,332	$	88	$	(6	)	$	52,414
Due in one to three years		59,176		137		(37	)		59,276
U.S. treasury and government agency securities
Due in one year or less		24,795		86		—			24,881
Due in one to three years		34,606		84		(2	)		34,688
Commercial paper
Due in one year or less		9,494		1		(4	)		9,491
Total investments	$	180,403	$	396	$	(49	)	$	180,750