Related party transactions - Related Party Revenue (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Related Party Transaction [Line Items]
Revenues	$ 449	$ 377	$ 807	$ 712
Related Party
Related Party Transaction [Line Items]
Revenues	82	79	157	158
Management fee revenues \| Related Party
Related Party Transaction [Line Items]
Revenues	64	62	124	120
Add-on services \| Related Party
Related Party Transaction [Line Items]
Revenues	3	3	6	6
Reimbursable revenues \| Related Party
Related Party Transaction [Line Items]
Revenues	7	6	11	16
Lease revenue \| Related Party
Related Party Transaction [Line Items]
Revenues	$ 8	$ 8	$ 16	$ 16

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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+ Details