Revenue - Disaggregation of Revenue by Performance Obligation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of revenue by performance obligation
Revenue	$ 1,011,911	$ 989,399
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	786,399	755,049
Management fee revenue - policy issuance and renewal services | Transferred at Point in Time
Disaggregation of revenue by performance obligation
Revenue	786,399	755,049
Total revenue from administrative services | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	219,571	227,918
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	19,475	17,645
Management fee revenue - administrative services | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	19,475	17,645
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	200,096	210,273
Administrative services reimbursement revenue | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	$ 200,096	$ 210,273