Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2019

Marketable Securities

Summary of marketable debt securities, classified as available-for-sale

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(In thousands)
December 31, 2019
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	18,509	$	13	$	—	$	18,522
Maturing after one year through three years		—		—		—		—
Total U.S. government and municipal obligations	$	18,509	$	13	$	—	$	18,522
Corporate debt securities
Maturing in one year or less	$	34,619	$	13	$	(3)	$	34,629
Maturing after one year through three years		—		—		—		—
Total corporate debt securities	$	34,619	$	13	$	(3)	$	34,629
Total marketable securities	$	53,128	$	26	$	(3)	$	53,151
December 31, 2018
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	27,355	$	—	$	(4)	$	27,351
Maturing after one year through three years		—		—		—		—
Total U.S. government and municipal obligations	$	27,355	$	—	$	(4)	$	27,351
Corporate debt securities
Maturing in one year or less	$	42,370	$	—	$	(9)	$	42,361
Maturing after one year through three years		—		—		—		—
Total corporate debt securities	$	42,370	$	—	$	(9)	$	42,361
Total marketable securities	$	69,725	$	—	$	(13)	$	69,712