Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [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 condensed consolidated balance sheets:

(In millions)	As of September 30, 2020		As of December 31, 2019
Commercial paper	$	649.2	$	384.4
Overnight reverse repurchase agreements	465.4		368.8
Money market funds	270.2		1,628.5
Short-term debt securities	185.5		159.4
Total	$	1,570.3	$	2,541.1

Marketable debt and equity securities

The following tables summarize our marketable debt and equity securities:

	As of September 30, 2020
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate debt securities:
Current	$	963.5	$	1.4	$	(0.1)	$	964.8
Non-current	475.9		3.2		(0.1)		479.0
Government securities:
Current	389.4		0.2		—		389.6
Non-current	376.4		1.4		—		377.8
Mortgage and other asset backed securities:
Current	0.6		—		—		0.6
Non-current	152.6		0.6		(0.2)		153.0
Total marketable debt securities	$	2,358.4	$	6.8	$	(0.4)	$	2,364.8
Marketable equity securities, non-current	$	851.7	$	63.6	$	(46.8)	$	868.5

	As of December 31, 2019
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate debt securities:
Current	$	1,057.2	$	1.0	$	—	$	1,058.2
Non-current	633.9		3.0		—		636.9
Government securities:
Current	502.9		0.4		—		503.3
Non-current	510.1		0.8		(0.3)		510.6
Mortgage and other asset backed securities:
Current	0.7		—		—		0.7
Non-current	260.2		0.8		(0.4)		260.6
Total marketable debt securities	$	2,965.0	$	6.0	$	(0.7)	$	2,970.3
Marketable equity securities, non-current	$	218.4	$	132.1	$	(13.0)	$	337.5

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 September 30, 2020				As of December 31, 2019
(In millions)	Estimated Fair Value		Amortized Cost		Estimated Fair Value		Amortized Cost
Due in one year or less	$	1,355.0	$	1,353.4	$	1,562.2	$	1,560.8
Due after one year through five years	902.2		897.9		1,234.5		1,230.4
Due after five years	107.6		107.1		173.6		173.8
Total marketable debt securities	$	2,364.8	$	2,358.4	$	2,970.3	$	2,965.0

Proceeds from marketable debt securities

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

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2020		2019		2020		2019
Proceeds from maturities and sales	$	1,360.9	$	611.8	$	5,240.7	$	3,867.6
Realized gains	1.0		0.7		12.8		2.3
Realized losses	(0.9)		(0.1)		(25.2)		(0.7)