Revenue - Disaggregation of Revenue by Performance Obligation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of revenue by performance obligation
Revenue	$ 990,438	$ 839,870	$ 1,871,139	$ 1,592,335
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	760,886	633,339	1,426,572	1,191,429
Management fee revenue - policy issuance and renewal services | Transferred At Point in Time
Disaggregation of revenue by performance obligation
Revenue	760,886	633,339	1,426,572	1,191,429
Administrative services | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	223,079	200,102	431,580	388,118
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	17,051	15,636	33,985	30,825
Management fee revenue - administrative services | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	17,051	15,636	33,985	30,825
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	206,028	184,466	397,595	357,293
Administrative services reimbursement revenue | Transferred Over Time
Disaggregation of revenue by performance obligation
Revenue	$ 206,028	$ 184,466	$ 397,595	$ 357,293