Cash, Cash Equivalents, and Marketable Debt Securities (Tables)

9 Months Ended

Sep. 30, 2024

Cash, Cash Equivalents, and Short-Term Investments [Abstract]

Schedule of Cash and Available-For-Sale Debt Securities by Major Asset Category

The following table shows the Company’s cash, cash equivalents, held-to-maturity ("HTM") debt securities, and available-for-sale ("AFS") debt securities by major asset category at September 30, 2024 and December 31, 2023 (in millions):

	September 30, 2024
	Adjusted Cost Basis		Unrealized Gain		Unrealized Loss		Fair Value		Cash and Cash Equivalents		Short-Term Marketable Debt Securities		Long-Term Marketable Debt Securities
Cash and cash equivalents	$	674.8	$	—	$	—	$	674.8	$	674.8	$	—	$	—
Level 1 (a):
U.S. Treasury securities		28.3		0.1		—		28.4		—		16.2		12.2
Money market funds		1.8		—		—		1.8		1.8		—		—
Subtotal		30.1		0.1		—		30.2		1.8		16.2		12.2
Level 2 (b):
Corporate debt securities		125.8		0.8		—		126.6		—		70.1		56.5
Certificates of deposit		6.7		—		—		6.7		—		6.7		—
U.S. government agency securities		3.0		—		—		3.0		—		2.0		1.0
Subtotal		135.5		0.8		—		136.3		—		78.8		57.5
Total	$	840.4	$	0.9	$	—	$	841.3	$	676.6	$	95.0	$	69.7

	December 31, 2023
	Adjusted Cost Basis		Unrealized Gain		Unrealized Loss			Fair Value		Cash and Cash Equivalents		Short-Term Marketable Debt Securities		Long-Term Marketable Debt Securities
Cash and cash equivalents	$	646.4	$	—	$	—		$	646.4	$	646.4	$	—	$	—
Time Deposits (c):		400.0		—		—			400.0		—		400.0		—
Level 1 (a):
U.S. Treasury securities		29.3		—		—			29.3		—		11.3		18.0
Money market funds		1.6		—		—			1.6		1.6		—		—
Subtotal		30.9		—		—			30.9		1.6		11.3		18.0
Level 2 (b):
Corporate debt securities		112.5		0.3		(0.4	)		112.4		—		68.5		43.9
U.S. government agency securities		10.1		—		(0.1	)		10.0		—		7.8		2.2
Certificates of deposit		5.9		—		—			5.9		—		5.9		—
Subtotal		128.5		0.3		(0.5	)		128.3		—		82.2		46.1
Total	$	1,205.8	$	0.3	$	(0.5	)	$	1,205.6	$	648.0	$	493.5	$	64.1

(a)Valuations based on quoted prices for identical assets or liabilities in active markets.

(b)Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.

(c)We had $400.0 million of investments in time deposits classified as HTM debt securities as of December 31, 2023, which matured within one year and were recorded in “Short-term marketable debt securities” on our Consolidated Balance Sheets. We recorded these HTM debt securities at amortized cost, which approximated fair value. We did not have any investments in HTM debt securities as of September 30, 2024, as the investments in time deposits matured on September 12, 2024. The proceeds received from the maturity of these time deposits were used to repay our 3.65% senior notes due 2024, which matured on September 15, 2024.

Schedule of Marketable Debt Securities in Continuous Loss Position

The following tables provide information about the Company’s marketable debt securities that have been in a continuous loss position as of September 30, 2024 and December 31, 2023 (in millions, except number of marketable debt securities in a loss position):

	September 30, 2024
	Fair Value of Marketable Debt Securities in a Loss Position < 12 Months		Number of Marketable Debt Securities in a Loss Position < 12 Months		Unrealized Losses < 12 Months (d)		Fair Value of Marketable Debt Securities in a Loss Position ≥ 12 Months		Number of Marketable Debt Securities in a Loss Position ≥ 12 Months		Unrealized Losses ≥ 12 Months (d)
Corporate debt securities	$	8.3		12	$	—	$	4.0		7	$	—
U.S. Treasury securities		—		—		—		9.0		8		—
U.S. government agency securities		2.0		3		—		—		—		—
	$	10.3		15	$	—	$	13.0		15	$	—

	December 31, 2023
	Fair Value of Marketable Debt Securities in a Loss Position < 12 Months		Number of Marketable Debt Securities in a Loss Position < 12 Months		Unrealized Losses < 12 Months		Fair Value of Marketable Debt Securities in a Loss Position ≥ 12 Months		Number of Marketable Debt Securities in a Loss Position ≥ 12 Months		Unrealized Losses ≥ 12 Months
Corporate debt securities	$	27.9		35	$	0.1	$	36.2		49	$	0.3
U.S. Treasury securities		11.4		11		—		6.2		10		0.1
U.S. government agency securities		8.5		14		—		1.5		2		—
	$	47.8		60	$	0.1	$	43.9		61	$	0.4

(d)Unrealized losses were insignificant for both debt securities in a continuous loss position less than 12 months and debt securities in a continuous loss position greater than or equal to 12 months for the period ended September 30, 2024.