Marketable Securities

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Marketable securities as of September 30, 2020 and December 31, 2019 consist of both available-for-sale debt securities of investment grade issuers (see below and Note 6) as well as equity securities of publicly traded companies (see Note 6).

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


	Amortized		Unrealized				Fair
As of September 30, 2020	Cost Basis		Gains		Losses		Value
Corporate bonds	$	2,796.6	$	40.1	$	(0.7)	$	2,836.0
U.S. government and government agency obligations	133.5		1.3		(0.1)		134.7
Sovereign bonds	65.4		1.2		—		66.6
Commercial paper	390.4		0.2		—		390.6
Certificates of deposit	122.4		0.1		—		122.5
	$	3,508.3	$	42.9	$	(0.8)	$	3,550.4

As of December 31, 2019
Corporate bonds	$	3,960.5	$	27.8	$	(0.2)	$	3,988.1
U.S. government and government agency obligations	54.3		0.2		(0.1)		54.4
Sovereign bonds	26.9		0.4		—		27.3
Commercial paper	92.3		—		—		92.3
Certificates of deposit	72.3		0.1		—		72.4
	$	4,206.3	$	28.5	$	(0.3)	$	4,234.5

The Company classifies its investments in available-for-sale debt securities based on their contractual maturity dates. The available-for-sale debt securities listed as of September 30, 2020 mature at various dates through September 2025. The fair values of available-for-sale debt security investments by contractual maturity consist of the following:


	September 30,		December 31,
	2020		2019
Maturities within one year	$	1,452.9	$	1,596.5
Maturities after one year through five years	2,097.5		2,638.0
	$	3,550.4	$	4,234.5

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
As of September 30, 2020	Fair Value		Unrealized Loss		Fair Value	Unrealized Loss	Fair Value		Unrealized Loss
Corporate bonds	$	560.5	$	(0.7)	—	—	$	560.5	$	(0.7)
U.S. government and government agency obligations	45.5		(0.1)		—	—	45.5		(0.1)
	$	606.0	$	(0.8)	—	—	$	606.0	$	(0.8)

As of December 31, 2019
Corporate bonds	$	257.2	$	(0.2)	—	—	$	257.2	$	(0.2)
U.S. government and government agency obligations	17.3		(0.1)		—	—	17.3		(0.1)
	$	274.5	$	(0.3)	—	—	$	274.5	$	(0.3)

For the three months ended September 30, 2020, realized gains on sales of marketable securities were not material. For the nine months ended September 30, 2020, realized gains were $28.5 million. Realized losses were not material for the three and nine months ended September 30, 2020. There were no realized losses on sales of marketable securities, and realized gains were not material, for the three and nine months ended September 30, 2019.

With respect to marketable securities, for the three and nine months ended September 30, 2020 and 2019, amounts reclassified from Accumulated other comprehensive income into Other (expense) income, net were related to realized gains and losses on sales of available-for-sale debt securities (as described above).