Marketable Securities

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

All marketable securities were considered available-for-sale at December 31, 2022 and 2021. On a recurring basis, the Company records its marketable securities at fair value using Level 1 or Level 2 inputs as discussed in Note 2, "Fair Value Measurements". The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s marketable securities by major security type at each balance sheet date are summarized in the tables below (in thousands):

	December 31, 2022
	Amortized Cost		Unrealized Holding Gains		Unrealized Holding Losses		Aggregate Fair Value
Short-term marketable securities:
U.S. government treasuries(1)	$	1,009,733	$	58	$	(6,287)	$	1,003,504
U.S. government agency securities	16,823		38		—		16,861
Corporate debt securities(2)	54,571		—		(356)		54,215
Commercial paper	43,591		—		—		43,591
Total short-term marketable securities	1,124,718		96		(6,643)		1,118,171
Total	$	1,124,718	$	96	$	(6,643)	$	1,118,171

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(1)Unrealized holding losses on 51 securities with an aggregate fair value of $683.4 million.

(2)Unrealized holding losses on 16 securities with an aggregate fair value of $54.2 million.

	December 31, 2021
	Amortized Cost		Unrealized Holding Gains		Unrealized Holding Losses		Aggregate Fair Value
Short-term marketable securities:
U.S. government treasuries(1)	$	450,689	$	—	$	(253)	$	450,436
Corporate debt securities(2)	70,076		1		(68)		70,009
Commercial paper	51,485		—		—		51,485
Total short-term marketable securities	572,250		1		(321)		571,930
Long-term marketable securities:
U.S. government treasuries(3)	411,904		—		(1,757)		410,147
Corporate debt securities(4)	15,373		—		(71)		15,302
Total long-term marketable securities	427,277		—		(1,828)		425,449
Total	$	999,527	$	1	$	(2,149)	$	997,379

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(1)Unrealized holding losses on 19 securities with an aggregate fair value of $450.4 million.

(2)Unrealized holding losses on 16 securities with an aggregate fair value of $68.5 million.

(3)Unrealized holding losses on 16 securities with an aggregate fair value of $410.1 million.

(4)Unrealized holding losses on 6 securities with an aggregate fair value of $15.3 million.

As of December 31, 2022 and 2021, a majority of the Company's marketable securities were in an unrealized loss position. The Company has not recognized an allowance for credit losses as of December 31, 2022 or 2021. The Company determined that it had the ability and intent to hold all marketable securities that have been in a continuous loss position until maturity or recovery. Further, a majority of these securities are held in U.S. government securities, and the remainder were initially, and continue to be, held with investment grade, high credit quality institutions. All marketable securities with unrealized losses as of each balance sheet date have been in a loss position for less than twelve months or the loss is not material.

As of December 31, 2022 all of the Company’s marketable securities have an effective maturity of less than one year.