Investments (Tables)

6 Months Ended

Jun. 30, 2023

Investments [Abstract]

Schedule of available-for-sale debt securities

Available-for-sale debt securities are recorded at fair value, with the portion of the unrealized gains and losses that are not credit-related included as a component of accumulated other comprehensive loss in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions):

As of June 30, 2023	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government and agency securities	$	3,017.9	$	—	$	(49.5)	$	2,968.4
Corporate debt securities	670.7		—		(13.7)		657.0
Total	$	3,688.6	$	—	$	(63.2)	$	3,625.4

Reported under the following captions in our consolidated balance sheets:
Cash and cash equivalents	$	10.4
Current marketable investments	1,591.4
Non-current marketable investments	2,023.6
Total	$	3,625.4

As of December 31, 2022	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government and agency securities	$	2,697.8	$	0.1	$	(58.9)	$	2,639.0
Corporate debt securities	555.6		—		(16.0)		539.6
Total(1)	$	3,253.4	$	0.1	$	(74.9)	$	3,178.6

Reported under the following captions in our consolidated balance sheets:
Cash and cash equivalents	$	15.6
Current marketable investments	1,846.8
Non-current marketable investments	1,316.2
Total(1)	$	3,178.6

(1)Total excludes $70.0 million related to available-for-sale debt securities that matured on December 31, 2022, although cash proceeds were not received until January 3, 2023. We recorded the $70.0 million receivable within other current assets in our consolidated balance sheets as of December 31, 2022.

Schedule of available-for-sale debt securities in an unrealized loss position

The following tables present gross unrealized losses and fair value for those available-for-sale debt securities that were in an unrealized loss position as of June 30, 2023 and December 31, 2022, aggregated by investment category and length of time that the individual securities have been in a continuous loss position (in millions):

	Less than 12 months				12 months or longer				Total
As of June 30, 2023	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. government and agency securities	$	1,783.1	$	(19.6)	$	1,159.3	$	(29.9)	$	2,942.4	$	(49.5)
Corporate debt securities	321.9		(3.9)		329.1		(9.8)		651.0		(13.7)
Total	$	2,105.0	$	(23.5)	$	1,488.4	$	(39.7)	$	3,593.4	$	(63.2)

	Less than 12 months				12 months or longer				Total
As of December 31, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. government and agency securities	$	1,324.6	$	(24.2)	$	1,111.6	$	(34.7)	$	2,436.2	$	(58.9)
Corporate debt securities	254.2		(6.7)		274.1		(9.3)		528.3		(16.0)
Total	$	1,578.8	$	(30.9)	$	1,385.7	$	(44.0)	$	2,964.5	$	(74.9)

Summary of the contractual maturities

The following table summarizes the contractual maturities of available-for-sale debt securities (in millions). Actual maturities may differ from contractual maturities because the issuers of certain of these debt securities have the right to call the securities or prepay their obligations under the securities with or without penalties.

	As of June 30, 2023
	Amortized Cost		Fair Value
Due within one year	$	1,624.8	$	1,601.8
Due in one to three years	2,063.8		2,023.6
Total	$	3,688.6	$	3,625.4