Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2013

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
September 30, 2013
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	50,900	$	32	$	(3	)	$	50,929
Maturing after one year through three years	14,104		63		(2		)	14,165
Total U.S. government and municipal obligations	$	65,004	$	95	$	(5	)	$	65,094
Corporate debt securities
Maturing in one year or less	$	36,001	$	13	$	(4	)	$	36,010
Maturing after one year through three years	20,857		9		(8		)	20,858
Total corporate debt securities	$	56,858	$	22	$	(12	)	$	56,868
Total marketable securities	$	121,862	$	117	$	(17	)	$	121,962
December 31, 2012
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	15,566	$	28	$	—		$	15,594
Maturing after one year through three years	19,797		99		(1		)	19,895
Total U.S. government and municipal obligations	$	35,363	$	127	$	(1	)	$	35,489
Corporate debt securities
Maturing in one year or less	$	17,353	$	23	$	(4	)	$	17,372
Maturing after one year through three years	6,193		14		(3		)	6,204
Total corporate debt securities	$	23,546	$	37	$	(7	)	$	23,576
Total marketable securities	$	58,909	$	164	$	(8	)	$	59,065