Reinsurance - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 06, 2020	Dec. 31, 2023	Dec. 31, 2020	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2022
Ceded Credit Risk [Line Items]
Premiums receivable balance, credit provisions		$ 3,000		$ 2,008	$ 2,742	$ 2,008	$ 2,742	$ 3,000	$ 1,962	$ 3,098	$ 2,856
Premiums receivable		658,363		885,744		885,744		658,363
Paid losses recoverable		145,202		146,008		146,008		145,202
Unpaid losses and loss adjustment expenses recoverable		1,161,077		1,190,465	1,157,123	1,190,465	1,157,123	1,161,077			1,177,863
Reinsurance recoverable, provisions		687		833	691	833	691	687	$ 755	$ 820	$ 777
Reinsurance premiums ceded				75,505	90,557	410,802	400,475
Related Party
Ceded Credit Risk [Line Items]
Reinsurance premiums ceded				0	0	14,600	7,200
Risk transfer capacity		200,000	$ 150,000
Reinsurance Contract [Axis]: Loss Portfolio Transfer Agreement
Ceded Credit Risk [Line Items]
Unpaid losses and loss adjustment expenses recoverable		$ 49,800		44,200		44,200		$ 49,800
Reinsurance premiums ceded	$ 72,100
Amortization of the deferred gain				$ (600)	$ (900)	$ 1,300	$ 2,500
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						100.00%		100.00%
Reinsurer One | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						24.00%		27.00%
Reinsurer Two | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						21.00%		20.00%
Reinsurer Three | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						13.00%		12.00%