Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Available-for-sale Debt Securities

The following tables summarize the Company's investments in available-for-sale debt securities:

(In millions)	Amortized		Unrealized				Fair
As of September 30, 2023	Cost Basis		Gains		Losses		Value
Corporate bonds	$	6,726.3	$	0.4	$	(189.1)	$	6,537.6
U.S. government and government agency obligations	5,112.6		0.2		(30.5)		5,082.3
Sovereign bonds	67.3		—		(1.7)		65.6
Commercial paper	505.1		0.2		(0.2)		505.1
Certificates of deposit	342.6		0.1		(0.1)		342.6
Asset-backed securities	89.6		—		(2.4)		87.2
	$	12,843.5	$	0.9	$	(224.0)	$	12,620.4
As of December 31, 2022
Corporate bonds	$	6,975.5	$	—	$	(291.1)	$	6,684.4
U.S. government and government agency obligations	2,945.4		0.9		(6.9)		2,939.4
Sovereign bonds	67.1		—		(3.0)		64.1
Commercial paper	121.1		—		—		121.1
Certificates of deposit	182.1		—		(0.1)		182.0
Asset-backed securities	28.9		—		(1.7)		27.2
	$	10,320.1	$	0.9	$	(302.8)	$	10,018.2

Marketable Securities, Based on Contractual Maturity Dates

The fair values of available-for-sale debt securities by contractual maturity consist of the following:

	September 30,		December 31,
(In millions)	2023		2022
Maturities within one year	$	7,786.0	$	4,636.4
Maturities after one year through five years	4,830.0		5,381.4
Maturities after five years	4.4		0.4
	$	12,620.4	$	10,018.2

Fair Value and Unrealized Losses of Marketable Securities

The following table shows the fair value of the Company's available-for-sale debt securities that have unrealized losses, aggregated by investment category and length of time that the individual securities have been in a continuous loss position.

	Less than 12 Months				12 Months or Greater				Total
(In millions) As of September 30, 2023	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate bonds	$	1,976.1	$	(23.8)	$	4,387.1	$	(165.3)	$	6,363.2	$	(189.1)
U.S. government and government agency obligations	2,794.8		(26.8)		51.7		(3.7)		2,846.5		(30.5)
Sovereign bonds	12.2		(0.2)		53.3		(1.5)		65.5		(1.7)
Commercial paper	431.8		(0.2)		—		—		431.8		(0.2)
Certificates of deposit	136.3		(0.1)		—		—		136.3		(0.1)
Asset-backed securities	62.3		(1.1)		24.9		(1.3)		87.2		(2.4)
	$	5,413.5	$	(52.2)	$	4,517.0	$	(171.8)	$	9,930.5	$	(224.0)
As of December 31, 2022
Corporate bonds	$	2,445.4	$	(73.1)	$	4,200.4	$	(218.0)	$	6,645.8	$	(291.1)
U.S. government and government agency obligations	785.2		(2.0)		71.0		(4.9)		856.2		(6.9)
Sovereign bonds	18.6		(1.1)		45.6		(1.9)		64.2		(3.0)
Certificates of deposit	40.2		(0.1)		—		—		40.2		(0.1)
Asset-backed securities	11.5		(0.6)		15.2		(1.1)		26.7		(1.7)
	$	3,300.9	$	(76.9)	$	4,332.2	$	(225.9)	$	7,633.1	$	(302.8)