Basis of Presentation and Summary of Significant Accounting Policies - Reinsurance - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Amount of allowance for uncollectible amounts on paid recoverables	$ 19,000,000	$ 16,000,000
Reinsurance balances recoverable on unpaid losses and settlement expenses, allowances for uncollectible amounts	11,131,000	$ 11,250,000
Financing receivable, allowance for credit Loss, write-off	0
Amount of allowance for uncollectible amounts due beyond one year	$ 0
Threshold period for including reinsurance receivables in the allowance for uncollectible amounts	1 year