Marketable Securities

9 Months Ended

Sep. 30, 2021

Marketable Securities

Marketable Securities

(4)  Marketable Securities

The following is a summary of marketable debt securities, classified as available-for-sale:

	Gross Unrealized
	Amortized						Fair
	Cost		Gains		Losses		Value
	(In thousands)
September 30, 2021
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	24,291	$	5	$	—	$	24,296
Maturing after one year through three years		75,314		2		(17)		75,299
Total U.S. government and municipal obligations	$	99,605	$	7	$	(17)	$	99,595
Corporate debt securities
Maturing in one year or less	$	183,504	$	—	$	(10)	$	183,494
Maturing after one year through three years		67,844		8		(36)		67,816
Total corporate debt securities	$	251,348	$	8	$	(46)	$	251,310
Total marketable securities	$	350,953	$	15	$	(63)	$	350,905
	Gross Unrealized
	Amortized						Fair
	Cost		Gains		Losses		Value
	(In thousands)
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

The Company holds investment-grade marketable securities, and none were in a continuous unrealized loss position for more than twelve months as of September 30, 2021 and December 31, 2020. The unrealized losses are attributable to changes in interest rates and the Company does not believe any unrealized losses represent other-than-temporary impairments. Marketable securities include $0.8 million and $0.2 million in accrued interest at September 30, 2021 and December 31, 2020, respectively.