Reinsurance - Summary of Quota Reinsurance Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effects of Reinsurance [Line Items]
Ceded losses incurred	$ (3,598)	$ 20,707	$ 13,710	$ 65,462
Quota Share Reinsurance Agreements, Excluding Captive Agreements
Effects of Reinsurance [Line Items]
Ceded premiums written and earned, net of profit commission	22,911	43,448	90,284	131,651
Ceded losses incurred	(3,598)	20,707	13,710	65,493
Ceding commissions	13,599	12,128	39,657	35,518
Profit commission	$ 45,078	$ 17,191	$ 108,000	$ 45,939