Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2015

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
June 30, 2015
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	56,882	$	22	$	(3	)	$	56,901
Maturing after one year through three years	12,120		30		(53		)	12,097
Total U.S. government and municipal obligations	$	69,002	$	52	$	(56	)	$	68,998
Corporate debt securities
Maturing in one year or less	$	120,267	$	12	$	(92	)	$	120,187
Maturing after one year through three years	63,299		9		(85		)	63,223
Total corporate debt securities	$	183,566	$	21	$	(177	)	$	183,410
Total marketable securities	$	252,568	$	73	$	(233	)	$	252,408
December 31, 2014
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	44,580	$	30	$	(6	)	$	44,604
Maturing after one year through three years	16,108		49		(1		)	16,156
Total U.S. government and municipal obligations	$	60,688	$	79	$	(7	)	$	60,760
Corporate debt securities
Maturing in one year or less	$	89,636	$	6	$	(37	)	$	89,605
Maturing after one year through three years	22,690		3		(35		)	22,658
Total corporate debt securities	$	112,326	$	9	$	(72	)	$	112,263
Total marketable securities	$	173,014	$	88	$	(79	)	$	173,023