Fair value of financial instruments - Narrative (Details) $ in Millions	6 Months Ended
Jun. 30, 2026 USD ($)
G4S
Derivative [Line Items]
Contingent consideration	$ 24
Foreign Exchange Contract \| Not Designated as Hedging Instrument
Derivative [Line Items]
Notional value of nonderivative instruments	$ 664
Weighted average maturity	1 month
$215 million cross currency swap II \| Designated as Hedging Instrument
Derivative [Line Items]
Notional value of derivative instrument	$ 215
$215 million cross currency swap III \| Designated as Hedging Instrument
Derivative [Line Items]
Weighted average maturity	9 months 18 days
Notional value of derivative instrument	$ 215
$150 million interest rate swap \| Designated as Hedging Instrument
Derivative [Line Items]
Weighted average maturity	6 months
Notional value of derivative instrument	$ 150

Amount of liability recognized arising from contingent consideration in a business combination.

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