Summary of Significant Accounting Policies - Allowance for Credit Losses on Premium Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 5,800	$ 6,000	$ 10,000
Provision during the period for expected credit losses	2,819	4,213	(893)
Write-off amounts during the period	(3,879)	(5,027)	(3,693)
Recoveries during the period of amounts previously written off	560	614	586
Ending balance	$ 5,300	$ 5,800	$ 6,000