Segment information - Schedule of Assets by Segment (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Segment Reporting [Line Items]
Assets	$ 8,943.3	$ 8,263.1
Corporate and eliminations
Segment Reporting [Line Items]
Assets	(564.0)	(427.2)
Exchange Services \| Operating Segments
Segment Reporting [Line Items]
Assets	1,156.0	903.9
MGA Operations \| Operating Segments
Segment Reporting [Line Items]
Assets	528.1	479.2
Underwriting \| Operating Segments
Segment Reporting [Line Items]
Assets	$ 7,823.2	$ 7,307.2

Amount of asset recognized for present right to economic benefit.

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+ Details

- Definition

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.

+ References

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+ Details