Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2017

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
December 31, 2016
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	52,754	$	5	$	(12	)	$	52,747
Maturing after one year through three years	296		8		—			304
Total U.S. government and municipal obligations	$	53,050	$	13	$	(12	)	$	53,051
Corporate debt securities
Maturing in one year or less	$	94,320	$	—	$	(56	)	$	94,264
Maturing after one year through three years	—		—		—			—
Total corporate debt securities	$	94,320	$	—	$	(56	)	$	94,264
Total marketable securities	$	147,370	$	13	$	(68	)	$	147,315
March 31, 2017
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	35,515	$	2	$	(9	)	$	35,508
Maturing after one year through three years	153		6		—			159
Total U.S. government and municipal obligations	$	35,668	$	8	$	(9	)	$	35,667
Corporate debt securities
Maturing in one year or less	$	83,864	$	4	$	(38	)	$	83,830
Maturing after one year through three years	5,028		3		(2		)	5,029
Total corporate debt securities	$	88,892	$	7	$	(40	)	$	88,859
Total marketable securities	$	124,560	$	15	$	(49	)	$	124,526