Revenue - Disaggregation of Revenues By Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of revenue by performance obligation
Revenue	$ 726,143	$ 680,030	$ 1,398,253	$ 1,310,207
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	544,555	502,271	1,032,547	957,989
Management fee revenue - policy issuance and renewal services | Transferred at point in time
Disaggregation of revenue by performance obligation
Revenue	544,555	502,271	1,032,547	957,989
Administrative services | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	175,151	171,857	352,791	340,237
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	14,476	14,667	28,789	29,514
Management fee revenue - administrative services | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	14,476	14,667	28,789	29,514
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	160,675	157,190	324,002	310,723
Administrative services reimbursement revenue | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	$ 160,675	$ 157,190	$ 324,002	$ 310,723