Revenue - Disaggregation of Revenues By Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of revenue by performance obligation
Revenue	$ 839,870	$ 726,143	$ 1,592,335	$ 1,398,253
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	633,339	544,555	1,191,429	1,032,547
Management fee revenue - policy issuance and renewal services | Transferred At Point in Time
Disaggregation of revenue by performance obligation
Revenue	633,339	544,555	1,191,429	1,032,547
Administrative services | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	200,102	175,151	388,118	352,791
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	15,636	14,476	30,825	28,789
Management fee revenue - administrative services | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	15,636	14,476	30,825	28,789
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	184,466	160,675	357,293	324,002
Administrative services reimbursement revenue | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	$ 184,466	$ 160,675	$ 357,293	$ 324,002