Revenue - Disaggregation of Revenue by Performance Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of revenue by performance obligation
Revenue	$ 4,067,258	$ 3,795,115	$ 3,268,940
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	3,131,806	2,894,074	2,442,073
Management fee revenue - policy issuance and renewal services \| Transferred at point in time
Disaggregation of revenue by performance obligation
Revenue	3,131,806	2,894,074	2,442,073
Administrative services \| Transferred over time
Disaggregation of revenue by performance obligation
Revenue	910,697	874,691	800,808
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	74,058	68,355	63,669
Management fee revenue - administrative services \| Transferred over time
Disaggregation of revenue by performance obligation
Revenue	74,058	68,355	63,669
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	836,639	806,336	737,139
Administrative services reimbursement revenue \| Transferred over time
Disaggregation of revenue by performance obligation
Revenue	$ 836,639	$ 806,336	$ 737,139

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, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details