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, 2022		Dec. 31, 2021
Financial Instruments [Line Items]
Adjusted Cost Basis		$ 796.7		$ 765.2
Unrealized Gain		0.0		0.0
Unrealized Loss		(3.2)		(0.4)
Fair Value		793.5		764.8
Cash and cash equivalents		648.7		618.7
Short-term marketable debt securities		77.7		86.1
Long-term marketable debt securities		67.1		60.0
Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis		30.7		27.3
Unrealized Gain		0.0		0.0
Unrealized Loss		(0.6)		(0.1)
Fair Value		30.1		27.2
Cash and cash equivalents		3.7		2.9
Short-term marketable debt securities		13.7		14.7
Long-term marketable debt securities		12.7		9.6
Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis		123.0		125.6
Unrealized Gain		0.0		0.0
Unrealized Loss		(2.6)		(0.3)
Fair Value		120.4		125.3
Cash and cash equivalents		2.0		3.5
Short-term marketable debt securities		64.0		71.4
Long-term marketable debt securities		54.4		50.4
U.S. Government Agency Securities | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis		3.2	[1]	4.8	[2]
Unrealized Gain		0.0		0.0
Unrealized Loss		(0.1)		0.0
Fair Value	[1]	3.1		4.8
Cash and cash equivalents		0.0		0.0
Short-term marketable debt securities	[1]	1.2		3.5
Long-term marketable debt securities	[1]	1.9		1.3
Corporate Debt Securities | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis		117.0	[1]	118.9	[2]
Unrealized Gain		0.0		0.0
Unrealized Loss	[1]	(2.5)		(0.3)
Fair Value	[1]	114.5		118.6
Cash and cash equivalents	[1]	1.2		3.5
Short-term marketable debt securities	[1]	60.8		66.0
Long-term marketable debt securities	[1]	52.5		49.1
Cash and Cash Equivalents
Financial Instruments [Line Items]
Adjusted Cost Basis		643.0		612.3
Unrealized Gain		0.0		0.0
Unrealized Loss		0.0		0.0
Fair Value		643.0		612.3
Cash and cash equivalents		643.0		612.3
Short-term marketable debt securities		0.0		0.0
Long-term marketable debt securities		0.0		0.0
Money Market Fund | Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	0.7		0.9
Unrealized Gain		0.0	[2]	0.0
Unrealized Loss		0.0		0.0
Fair Value	[2]	0.7		0.9
Cash and cash equivalents	[2]	0.7		0.9
Short-term marketable debt securities		0.0		0.0
Long-term marketable debt securities		0.0		0.0
U.S. Treasury Securities | Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	30.0		26.4
Unrealized Gain		0.0	[2]	0.0
Unrealized Loss	[2]	(0.6)		(0.1)
Fair Value	[2]	29.4		26.3
Cash and cash equivalents	[2]	3.0		2.0
Short-term marketable debt securities	[2]	13.7		14.7
Long-term marketable debt securities	[2]	12.7		9.6
Certificates of Deposit | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis		2.8	[1]	1.9	[2]
Unrealized Gain		0.0		0.0
Unrealized Loss		0.0		0.0
Fair Value	[1]	2.8		1.9
Cash and cash equivalents		0.8	[1]	0.0
Short-term marketable debt securities	[1]	2.0		1.9
Long-term marketable debt securities		$ 0.0		$ 0.0

[1] 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.

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