Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2014

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
March 31, 2014
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	40,967	$	32	$	—		$	40,999
Maturing after one year through three years	43,248		84		(23		)	43,309
Total U.S. government and municipal obligations	$	84,215	$	116	$	(23	)	$	84,308
Corporate debt securities
Maturing in one year or less	$	96,375	$	38	$	(29	)	$	96,384
Maturing after one year through three years	36,651		12		(31		)	36,632
Total corporate debt securities	$	133,026	$	50	$	(60	)	$	133,016
Total marketable securities	$	217,241	$	166	$	(83	)	$	217,324
December 31, 2013
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	55,531	$	27	$	(4	)	$	55,554
Maturing after one year through three years	18,234		56		(4		)	18,286
Total U.S. government and municipal obligations	$	73,765	$	83	$	(8	)	$	73,840
Corporate debt securities
Maturing in one year or less	$	38,973	$	9	$	(9	)	$	38,973
Maturing after one year through three years	20,761		12		(5		)	20,768
Total corporate debt securities	$	59,734	$	21	$	(14	)	$	59,741
Total marketable securities	$	133,499	$	104	$	(22	)	$	133,581