Cash Equivalents and Investments (Tables)

12 Months Ended

Dec. 31, 2020

Cash Equivalents and Investments [Abstract]

Unrealized gains and losses and fair value of available-for-sale debt securities

The following table summarizes the Company's unrealized gains and losses and fair value of investments designated as available-for-sale debt securities as of December 31, 2020 and December 31, 2019 (in millions):

	As of December 31, 2020								As of December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Fixed income securities:
Asset-backed securities	$	76.5	$	0.2	$	—	$	76.7	$	81.3	$	0.1	$	—	$	81.4
Certificates of deposit	32.9		—		—		32.9		38.6		—		—		38.6
Commercial paper	89.3		—		—		89.3		168.2		—		—		168.2
Corporate debt securities	632.0		5.5		(0.1)		637.4		604.9		0.7		(0.1)		605.5
Foreign government debt securities	4.6		—		—		4.6		11.4		—		—		11.4
Time deposits	255.6		—		—		255.6		226.3		—		—		226.3
U.S. government agency securities	65.3		0.2		—		65.5		89.0		—		—		89.0
U.S. government securities	232.8		1.0		—		233.8		394.3		0.3		(0.1)		394.5
Total fixed income securities	1,389.0		6.9		(0.1)		1,395.8		1,614.0		1.1		(0.2)		1,614.9
Privately-held debt and redeemable preferred stock securities	18.3		37.4		—		$	55.7	19.1		37.4		—		56.5
Total available-for-sale debt securities	$	1,407.3	$	44.3	$	(0.1)	$	1,451.5	$	1,633.1	$	38.5	$	(0.2)	$	1,671.4
Reported as:
Cash equivalents	$	333.7	$	—	$	—	$	333.7	$	290.9	$	—	$	—	$	290.9
Short-term investments	404.3		1.2		—		405.5		733.7		0.5		—		734.2
Long-term investments	651.0		5.7		(0.1)		656.6		589.4		0.6		(0.2)		589.8
Other long-term assets	18.3		37.4		—		55.7		19.1		37.4		—		56.5
Total	$	1,407.3	$	44.3	$	(0.1)	$	1,451.5	$	1,633.1	$	38.5	$	(0.2)	$	1,671.4

Maturities of fixed income securities

The following table presents the contractual maturities of the Company's total fixed income securities as of December 31, 2020 (in millions):

	Amortized Cost		Estimated Fair Value
Due in less than one year	$	738.0	$	739.2
Due between one and five years	651.0		656.6
Total	$	1,389.0	$	1,395.8

Available-for-sale investments in an unrealized loss position

The following tables present the Company's total fixed income securities that were in an unrealized loss position as of December 31, 2020 and December 31, 2019 (in millions):

	As of December 31, 2020
	Less than 12 Months				12 Months or Greater				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Fixed income securities:
Asset-backed securities	$	17.5	$	—	$	—	$	—	$	17.5	$	—
Corporate debt securities	61.0		(0.1)		—		—		61.0		(0.1)
Foreign government debt securities	0.6		—		—		—		0.6		—
U.S. government securities	2.3		—		—		—		2.3		—
Total fixed income securities	$	81.4	$	(0.1)	$	—	$	—	$	81.4	$	(0.1)

	As of December 31, 2019
	Less than 12 Months				12 Months or Greater				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Fixed income securities:
Asset-backed securities	$	21.6	$	—	$	5.2	$	—	$	26.8	$	—
Corporate debt securities	142.6		(0.1)		2.1		—		144.7		(0.1)
Foreign government debt securities	4.0		—		4.0		—		8.0		—
U.S. government agency securities	20.0		—		—		—		20.0		—
U.S. government securities	71.6		(0.1)		—		—		71.6		(0.1)
Total fixed income securities	$	259.8	$	(0.2)	$	11.3	$	—	$	271.1	$	(0.2)

Schedule of investments in equity securities

The following table presents the Company's investments in equity securities as of December 31, 2020 and 2019 (in millions):

	As of December 31,
	2020		2019
Equity investments with readily determinable fair value
Money market funds	$	536.6	$	446.4
Mutual funds	29.3		26.8
Publicly-traded equity securities	6.6		3.8
Equity investments without readily determinable fair value	146.2		133.3
Total equity securities	$	718.7	$	610.3
Reported as:
Cash equivalents	$	519.8	$	442.3
Short-term investments	6.6		3.8
Prepaid expenses and other current assets	9.9		4.1
Other long-term assets	182.4		160.1
Total	$	718.7	$	610.3

Schedule of reconciliation of cash, cash equivalents and restricted cash

The following table provides a reconciliation of cash, cash equivalents, and restricted cash included in the Consolidated Balance Sheets as of December 31, 2020 and December 31, 2019 (in millions):

	As of December 31,
	2020		2019
Cash and cash equivalents	$	1,361.9	$	1,215.8
Restricted cash included in Prepaid expenses and other current assets	19.2		60.5
Restricted cash included in Other long-term assets	1.9		0.2
Total cash, cash equivalents, and restricted cash	$	1,383.0	$	1,276.5