Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2013

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(In thousands)
June 30, 2013
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	34,189	$	15	$	5	$	34,199
Maturing after one year through three years	34,030		61		22		34,069
Total U.S. government and municipal obligations	$	68,219	$	76	$	27	$	68,268
Corporate debt securities
Maturing in one year or less	$	33,336	$	10	$	32	$	33,314
Maturing after one year through three years	27,566		—		65		27,501
Total corporate debt securities	$	60,902	$	10	$	97	$	60,815
Total marketable securities	$	129,121	$	86	$	124	$	129,083
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