Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2021

Marketable Securities

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

	GrossUnrealized
	Amortized						Fair
	Cost		Gains		Losses		Value
	(In thousands)
March 31, 2021
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	16,338	$	4	$	—	$	16,342
Maturing after one year through three years		8,178		2		—		8,180
Total U.S. government and municipal obligations	$	24,516	$	6	$	—	$	24,522
Corporate debt securities
Maturing in one year or less	$	82,263	$	—	$	(15)	$	82,248
Maturing after one year through three years		—		—		—		—
Total corporate debt securities	$	82,263	$	—	$	(15)	$	82,248
Total marketable securities	$	106,779	$	6	$	(15)	$	106,770
December 31, 2020
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	40,328	$	3	$	(2)	$	40,329
Maturing after one year through three years		—		—		—		—
Total U.S. government and municipal obligations	$	40,328	$	3	$	(2)	$	40,329
Corporate debt securities
Maturing in one year or less	$	110,265	$	2	$	(10)	$	110,257
Maturing after one year through three years		—		—		—		—
Total corporate debt securities	$	110,265	$	2	$	(10)	$	110,257
Total marketable securities	$	150,593	$	5	$	(12)	$	150,586