Cash, Cash Equivalents, and Marketable Debt Securities - Schedule of Company's Cash and Available-For-Sale (AFS) Debt Securities by Major Asset Category (Details) - USD ($) $ in Millions		9 Months Ended		12 Months Ended
		Sep. 30, 2024		Dec. 31, 2023
Financial Instruments [Line Items]
Adjusted Cost Basis		$ 840.4		$ 1,205.8
Unrealized Gain		0.9		0.3
Unrealized Loss		(0.0)		(0.5)
Fair Value		841.3		1,205.6
Cash and cash equivalents		676.6		648.0
Short-Term Marketable Debt Securities		95.0		493.5
Long-term marketable debt securities		69.7		64.1
Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[1]	135.5		30.9
Unrealized Gain	[1]	0.8		0.0
Unrealized Loss	[1]	(0.0)		0.0
Fair Value	[1]	136.3		30.9
Cash and cash equivalents	[1]	0.0		1.6
Short-Term Marketable Debt Securities	[1]	78.8		11.3
Long-term marketable debt securities	[1]	57.5		18.0
Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis		30.1	[1]	128.5	[2]
Unrealized Gain		0.1	[1]	0.3	[2]
Unrealized Loss		(0.0)	[1]	(0.5)	[2]
Fair Value		30.2	[1]	128.3	[2]
Cash and cash equivalents		1.8	[1]	0.0	[2]
Short-Term Marketable Debt Securities		16.2	[1]	82.2	[2]
Long-term marketable debt securities		12.2	[1]	46.1	[2]
Cash and Cash Equivalents
Financial Instruments [Line Items]
Adjusted Cost Basis		674.8		646.4
Unrealized Gain		0.0		0.0
Unrealized Loss		0.0		0.0
Fair Value		674.8		646.4
Cash and cash equivalents		674.8		646.4
Short-Term Marketable Debt Securities		0.0		0.0
Long-term marketable debt securities		0.0		0.0
Time Deposits
Financial Instruments [Line Items]
Adjusted Cost Basis	[3]			400.0
Unrealized Gain	[3]			0.0
Unrealized Loss	[3]			0.0
Fair Value	[3]			400.0
Cash and cash equivalents	[3]			0.0
Short-Term Marketable Debt Securities	[3]			400.0
Long-term marketable debt securities	[3]			0.0
U.S. Treasury Securities | Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[1]	28.3		29.3
Unrealized Gain	[1]	0.1		0.0
Unrealized Loss	[1]	(0.0)		0.0
Fair Value	[1]	28.4		29.3
Cash and cash equivalents	[1]	0.0		0.0
Short-Term Marketable Debt Securities	[1]	16.2		11.3
Long-term marketable debt securities	[1]	12.2		18.0
Money Market Fund | Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[1]	1.8		1.6
Unrealized Gain	[1]	0.0		0.0
Unrealized Loss	[1]	0.0		0.0
Fair Value	[1]	1.8		1.6
Cash and cash equivalents	[1]	1.8		1.6
Short-Term Marketable Debt Securities	[1]	0.0		0.0
Long-term marketable debt securities	[1]	0.0		0.0
Corporate Debt Securities | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	125.8		112.5
Unrealized Gain	[2]	0.8		0.3
Unrealized Loss	[2]	(0.0)		(0.4)
Fair Value	[2]	126.6		112.4
Cash and cash equivalents	[2]	0.0		0.0
Short-Term Marketable Debt Securities	[2]	70.1		68.5
Long-term marketable debt securities	[2]	56.5		43.9
U.S. Government Agency Securities | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	3.0		10.1
Unrealized Gain	[2]	0.0		0.0
Unrealized Loss	[2]	0.0		(0.1)
Fair Value	[2]	3.0		10.0
Cash and cash equivalents	[2]	0.0		0.0
Short-Term Marketable Debt Securities	[2]	2.0		7.8
Long-term marketable debt securities	[2]	1.0		2.2
Certificates of Deposit | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	6.7		5.9
Unrealized Gain	[2]	0.0		0.0
Unrealized Loss	[2]	0.0		0.0
Fair Value	[2]	6.7		5.9
Cash and cash equivalents	[2]	0.0		0.0
Short-Term Marketable Debt Securities	[2]	6.7		5.9
Long-term marketable debt securities	[2]	$ 0.0		$ 0.0

[1] Valuations based on quoted prices for identical assets or liabilities in active markets.

[2] 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.

[3] 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.