Derivative and hedging activities - Gain (Loss) on Net Investment Hedges (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
3.875% unsecured notes \| Foreign currency denominated debt \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net investment hedges	$ (3.0)	$ 1.8	$ (13.7)	$ 9.3

Amount, before tax, of increase (decrease) in the cumulative translation adjustment from gain (loss) on foreign currency derivatives that are designated as, and are effective as, economic hedges of a net investment in a foreign entity.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481694/830-30-45-20

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 830
-SubTopic 20
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482014/830-20-35-3

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration