Reinsurance - Summary of Reinsurance Agreements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Premiums Earned, Net [Abstract]
Premiums earned, direct									$ 1,199,824	$ 1,155,240	$ 1,084,748
Premiums earned, assumed									10,848	5,085	1,805
Premiums earned, ceded									(188,729)	(129,337)	(111,391)
Net premiums earned	$ 261,367	$ 256,113	$ 243,562	$ 260,901	$ 266,267	$ 267,857	$ 247,102	$ 249,762	1,021,943	1,030,988	975,162
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, direct									442,194	130,100	43,060
Losses incurred, assumed									555	(125)	331
Losses incurred, ceded									(77,975)	(11,400)	(6,829)
Net losses incurred	$ 45,758	$ 40,686	$ 217,374	$ 60,956	$ 23,690	$ 33,985	$ 21,836	$ 39,064	$ 364,774	$ 118,575	$ 36,562