Reinsurance - Summary of Premiums Earned and Losses Incurred (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Premiums earned:
Direct	$ 300,557	$ 294,909	$ 896,346	$ 861,705
Assumed	2,729	1,388	8,719	3,275
Ceded (1)	(47,173)	(28,440)	(144,489)	(100,260)
Net premiums earned	256,113	267,857	760,576	764,720
Losses incurred:
Direct	61,164	36,755	383,950	102,835
Assumed	229	(34)	528	(110)
Ceded	(20,707)	(2,736)	(65,462)	(7,841)
Losses incurred, net	$ 40,686	$ 33,985	$ 319,016	$ 94,884