Financial Instruments Investments in Marketable Debt Securities (Tables)

12 Months Ended

Dec. 31, 2020

Cash Equivalents And Marketable Securities [Abstract]

Schedule of Investments in available-for-sale Debt Securities

As of December 31, 2020, the amortized cost, gross unrealized gains, gross unrealized losses and fair values of marketable debt securities which were considered as

available-for-sale,

by type of security were as follows (in thousands):


	December 31, 2020
	Weighted- Average Remaining Contractual Life (in years)		Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Corporate debt securities		0.3	$	54,789	$	2	$	(19	)	$	54,772
Mutual funds				35		2		—			37

Current portion				54,824		4		(19	)		54,809
Noncurrent:
Foreign bonds		5.7		861		89		—			950

Noncurrent portion				861		89		—			950

Total			$	55,685	$	93	$	(19	)	$	55,759

On December 31, 2019, the amortized cost, gross unrealized gains, gross unrealized losses and fair values of marketable debt securities which were considered as

available-for-sale,

by type of security were as follows (in thousands):


	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Corporate debt securities	$	32,382	$	10	$	(3	)	$	32,389
Foreign government bonds		1,007		—		—			1,007
Government-sponsored securities		2,752		—		(4	)		2,748
Mutual funds		36		—		—			36

Current portion		36,177		10		(7	)		36,180
Noncurrent:
Corporate debt securities		1,501		—		(4	)		1,497
Foreign bonds		664		—		—			664

Noncurrent portion		2,165		—		(4	)		2,161

Total	$	38,342	$	10	$	(11	)	$	38,341

Accumulated Unrealized Losses on Debt Securities Classified as Available-for-Sale in Continuous Loss Position

Accumulated unrealized losses on debt securities classified as

available-for-sale

that have been in a continuous loss position for less than 12months and for more than 12months as of December 31, 2020 and 2019, were as follows (in thousands):


	December 31, 2020
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Corporate debt securities	$	42,762	$	(19	)	$	—	$	—

Total	$	42,762	$	(19	)	$	—	$	—


	December 31, 2019
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Corporate debt securities	$	11,021	$	(3	)	$	1,497	$	(4	)
Government-sponsored securities		—		—			2,748		(4	)

Total	$	11,021	$	(3	)	$	4,245	$	(8	)

Schedule of Realized Gains and Losses on Sales of Available-for-Sale Debt Securities

We recognized realized gains and losses on sales of

available-for-sale

debt securities as follows (in thousands):


	Gross Realized Gains		Gross Realized Losses			Net Realized Gains (Losses)
2020	$	4	$	(13	)	$	(9	)
2019	$	4	$	(8	)	$	(4	)