Historical Loss and LAE Development - Reconciliation of Unpaid Losses and Settlement Expenses (LAE) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Unpaid losses and LAE at beginning of year
Gross	$ 2,315,637	$ 2,043,555	$ 1,750,049
Ceded	(740,089)	(608,086)	(443,729)
Net	1,575,548	1,435,469	1,306,320
Increase (decrease) in incurred losses and LAE
Current accident year	712,960	636,955	582,065
Prior accident years	(108,547)	(122,579)	(125,463)
Total incurred	604,413	514,376	456,602
Loss and LAE payments for claims incurred
Current accident year	(165,364)	(97,525)	(101,590)
Prior accident years	(325,921)	(276,772)	(225,863)
Total paid	(491,285)	(374,297)	(327,453)
Net unpaid losses and LAE at September 30	1,688,676	1,575,548	1,435,469
Unpaid losses and LAE at September 30
Gross	2,446,025	2,315,637	2,043,555
Ceded	(757,349)	(740,089)	(608,086)
Net unpaid losses and LAE at September 30	$ 1,688,676	$ 1,575,548	$ 1,435,469