Financial Instruments - Summary of financial assets with maturities of less than 90 days included within cash and cash equivalents (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Net Investment Income [Line Items]
Cash equivalents, at carrying value	$ 628.1	$ 2,233.2
Money market funds
Net Investment Income [Line Items]
Cash equivalents, at carrying value	628.1	2,027.7
Overnight reverse repurchase agreements
Net Investment Income [Line Items]
Cash equivalents, at carrying value	0.0	70.0
Short-term debt securities
Net Investment Income [Line Items]
Cash equivalents, at carrying value	0.0	15.4
Commercial Paper
Net Investment Income [Line Items]
Cash equivalents, at carrying value	$ 0.0	$ 120.1

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-8

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant