Cash and cash equivalents and short-term investments - Short-Term Investments (Detail) - EUR (€) € in Millions	Dec. 31, 2023	Dec. 31, 2022
Short Term Investments [Line Items]
Cash and cash equivalents	€ 7,004.7	€ 7,268.3
Short-term investments	5.4	107.7
Deposits with financial institutions, governments and government-related bodies
Short Term Investments [Line Items]
Cash and cash equivalents	1,348.7	2,548.1
Bank accounts
Short Term Investments [Line Items]
Cash and cash equivalents	2,488.6	1,523.5
Fair value, recurring
Short Term Investments [Line Items]
Investments in money market funds	3,167.4	3,196.7
Short-term investments	€ 5.4	€ 107.7

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes 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/2003/role/disclosureRef
-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/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-4

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