Revenue - Disaggregation of Revenues By Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of revenue by performance obligation
Revenue	$ 741,236	$ 687,839	$ 2,139,489	$ 1,998,046
Management fee revenue - policy issuance and renewal services
Disaggregation of revenue by performance obligation
Revenue	551,666	504,891	1,584,213	1,462,880
Management fee revenue - policy issuance and renewal services | Transferred at point in time
Disaggregation of revenue by performance obligation
Revenue	551,666	504,891	1,584,213	1,462,880
Administrative services | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	183,310	176,881	536,101	517,118
Management fee revenue - administrative services
Disaggregation of revenue by performance obligation
Revenue	14,657	14,471	43,446	43,985
Management fee revenue - administrative services | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	14,657	14,471	43,446	43,985
Administrative services reimbursement revenue
Disaggregation of revenue by performance obligation
Revenue	168,653	162,410	492,655	473,133
Administrative services reimbursement revenue | Transferred over time
Disaggregation of revenue by performance obligation
Revenue	$ 168,653	$ 162,410	$ 492,655	$ 473,133