Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Investments, All Other Investments [Abstract]

Summary of financial assets with maturities of less than 90 days included within cash and cash equivalents

The following table summarizes our financial assets with maturities of less than 90 days from the date of purchase included in cash and cash equivalents in our consolidated balance sheets:

	As of December 31,
(In millions)	2021		2020
Commercial paper	$	247.6	$	61.1
Overnight reverse repurchase agreements	200.0		37.4
Money market funds	901.6		505.1
Short-term debt securities	283.0		23.3
Total	$	1,632.2	$	626.9

Marketable debt and equity securities

The following tables summarize our marketable debt and equity securities, classified as available for sale:

	As of December 31, 2021
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Marketable debt securities:
Corporate debt securities:
Current	$	723.6	$	0.1	$	(0.3)	$	723.4
Non-current	385.4		0.2		(0.8)		384.8
Government securities:
Current	817.0		—		(0.4)		816.6
Non-current	377.0		0.1		(1.0)		376.1
Mortgage and other asset backed securities:
Current	1.1		—		—		1.1
Non-current	131.8		—		(0.7)		131.1
Total marketable debt securities	$	2,435.9	$	0.4	$	(3.2)	$	2,433.1
Marketable equity securities:
Marketable equity securities, current	$	33.9	$	9.9	$	—	$	43.8
Marketable equity securities, non-current	1,133.1		151.0		(279.4)		1,004.7
Total marketable equity securities	$	1,167.0	$	160.9	$	(279.4)	$	1,048.5

	As of December 31, 2020
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Marketable debt securities:
Corporate debt securities:
Current	$	897.8	$	0.4	$	(0.2)	$	898.0
Non-current	402.5		1.1		(0.1)		403.5
Government securities:
Current	380.6		0.1		—		380.7
Non-current	245.9		0.5		—		246.4
Mortgage and other asset backed securities:
Current	0.2		—		—		0.2
Non-current	122.1		0.2		(0.1)		122.2
Total marketable debt securities	$	2,049.1	$	2.3	$	(0.4)	$	2,051.0
Marketable equity securities:
Marketable equity securities, current	$	70.6	$	15.9	$	—	$	86.5
Marketable equity securities, non-current	1,168.9		733.8		(14.9)		1,887.8
Total marketable equity securities	$	1,239.5	$	749.7	$	(14.9)	$	1,974.3

Summary of contractual maturities: available-for-sale securities

The estimated fair value and amortized cost of our marketable debt securities available-for-sale by contractual maturity are summarized as follows:

	As of December 31, 2021				As of December 31, 2020
(In millions)	Estimated Fair Value		Amortized Cost		Estimated Fair Value		Amortized Cost
Due in one year or less	$	1,541.1	$	1,541.7	$	1,278.9	$	1,278.6
Due after one year through five years	868.2		870.2		722.6		721.3
Due after five years	23.8		24.0		49.5		49.2
Total marketable debt securities	$	2,433.1	$	2,435.9	$	2,051.0	$	2,049.1

Proceeds from marketable securities, excluding strategic investments

The proceeds from maturities and sales of marketable debt securities and resulting realized gains and losses are summarized as follows:

	For the Years Ended December 31,
(In millions)	2021		2020		2019
Proceeds from maturities and sales	$	3,405.4	$	7,299.4	$	6,007.0
Realized gains	0.2		17.7		6.0
Realized losses	4.0		26.0		1.5