Fair value of financial instruments - Narrative (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2026 |
Jun. 30, 2026 |
|
| G4S | ||
| Derivative [Line Items] | ||
| Contingent consideration derecognition gain | $ 22 | |
| Foreign Exchange Contract | Not Designated as Hedging Instrument | ||
| Derivative [Line Items] | ||
| Notional value of nonderivative instruments | $ 728 | |
| 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 | 7 months 6 days | |
| Notional value of derivative instrument | $ 215 | |
| $150 million interest rate swap | Designated as Hedging Instrument | ||
| Derivative [Line Items] | ||
| Weighted average maturity | 4 months 24 days | |
| Notional value of derivative instrument | $ 150 |