Revenue - Disaggregation of Revenues By Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of revenue by performance obligation
Revenue	$ 752,465	$ 672,110
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	558,090	487,992
Management fee revenue - policy issuance and renewal services | Transferred at point in time
Disaggregation of revenue by performance obligation
Revenue	558,090	487,992
Administrative services | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	188,016	177,640
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	15,189	14,313
Management fee revenue - administrative services | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	15,189	14,313
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	172,827	163,327
Administrative services reimbursement revenue | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	$ 172,827	$ 163,327