Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2016

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
September 30, 2016
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	61,179	$	28	$	(4	)	$	61,203
Maturing after one year through three years	334		12		—			346
Total U.S. government and municipal obligations	$	61,513	$	40	$	(4	)	$	61,549
Corporate debt securities
Maturing in one year or less	$	109,978	$	12	$	(34	)	$	109,956
Maturing after one year through three years	—		—		—			—
Total corporate debt securities	$	109,978	$	12	$	(34	)	$	109,956
Total marketable securities	$	171,491	$	52	$	(38	)	$	171,505
December 31, 2015
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	48,871	$	4	$	(20	)	$	48,855
Maturing after one year through three years	15,940		24		(57		)	15,907
Total U.S. government and municipal obligations	$	64,811	$	28	$	(77	)	$	64,762
Corporate debt securities
Maturing in one year or less	$	129,327	$	2	$	(141	)	$	129,188
Maturing after one year through three years	23,932		1		(102		)	23,831
Total corporate debt securities	$	153,259	$	3	$	(243	)	$	153,019
Total marketable securities	$	218,070	$	31	$	(320	)	$	217,781