Investments (Tables)

6 Months Ended

Jun. 30, 2021

Investments Debt And Equity Securities [Abstract]

Investments consisted of the following (in thousands):

			Gross Unrealized
					Losses
	Amortized				Less than			Greater than		Allowance for			Estimated
June 30, 2021	Cost		Gains		One Year			One Year		Credit Losses			Fair Value
Short-term investments:
Available-for-sale securities:
Corporate debt securities	$	136,404	$	570	$	(16	)	$	—	$	—		$	136,958
International government agency debt securities		72,982		190		(5	)		—		—			73,167
U.S. government and agency debt securities		67,868		139		—			—		—			68,007
		277,254		899		(21	)		—		—			278,132
Held-to-maturity securities:
Fixed term deposit account		1,667		205		—			—		—			1,872
Total short-term investments		278,921		1,104		(21	)		—		—			280,004
Long-term investments:
Available-for-sale securities:
Corporate debt securities		52,638		—		(46	)		—		—			52,592
International government agency debt securities		30,877		—		(46	)		—		—			30,831
U.S. government and agency debt securities		45,831		—		(42	)		—		—			45,789
		129,346		—		(134	)		—		—			129,212
Held-to-maturity securities:
Certificates of deposit		1,820		—		—			—		—			1,820
Total long-term investments		131,166		—		(134	)		—		—			131,032
Total investments	$	410,087	$	1,104	$	(155	)	$	—	$	—		$	411,036

December 31, 2020
Short-term investments:
Available-for-sale securities:
Corporate debt securities	$	176,937	$	1,105	$	(7	)	$	—	$	(977	)	$	177,058
U.S. government and agency debt securities		103,011		336		(2	)		—		—			103,345
International government agency debt securities		79,346		469		(6	)		—		—			79,809
		359,294		1,910		(15	)		—		(977	)		360,212
Held-to-maturity securities:
Fixed term deposit account		1,667		187		—			—		—			1,854
Total short-term investments		360,961		2,097		(15	)		—		(977	)		362,066
Long-term investments:
Available-for-sale securities:
Corporate debt securities		7,908		—		(10	)		—		—			7,898
International government agency debt securities		15,077		—		(15	)		—		—			15,062
		22,985		—		(25	)		—		—			22,960
Held-to-maturity securities:
Certificates of deposit		1,820		—		—			—		—			1,820
Total long-term investments		24,805		—		(25	)		—		—			24,780
Total investments	$	385,766	$	2,097	$	(40	)	$	—	$	(977	)	$	386,846

Schedule of Proceeds from Sales and Maturities of Marketable Securities Plus Resulting Realized Gains and Losses

The proceeds from sales and maturities of marketable securities, which were identified using the specific identification method and were primarily reinvested, were as follows:

	Six Months Ended June 30,
(In thousands)	2021		2020
Proceeds from the sales and maturities of marketable securities	$	175,499	$	147,859
Realized gains	$	—	$	51
Realized losses	$	977	$	—

Schedule of Contractual Maturities of Available-for-Sale and Held-to-Maturity Securities

The Company’s available-for-sale and held-to-maturity securities at June 30, 2021 had contractual maturities in the following periods:

	Available-for-sale				Held-to-maturity
	Amortized		Estimated		Amortized		Estimated
(In thousands)	Cost		Fair Value		Cost		Fair Value
Within 1 year	$	194,815	$	195,149	$	3,487	$	3,692
After 1 year through 5 years		211,785		212,195		—		—
Total	$	406,600	$	407,344	$	3,487	$	3,692