Reinsurance - Summary of Reinsurance Agreements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Premiums Earned, Net [Abstract]
Premiums earned, direct									$ 1,155,240	$ 1,084,748	$ 1,059,973
Premiums earned, assumed									5,085	1,805	509
Premiums earned, ceded									(129,337)	(111,391)	(125,735)
Net premiums earned	$ 266,267	$ 267,857	$ 247,102	$ 249,762	$ 245,665	$ 250,426	$ 246,964	$ 232,107	1,030,988	975,162	934,747
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, direct									130,100	43,060	74,727
Losses incurred, assumed									(125)	331	183
Losses incurred, ceded									(11,400)	(6,829)	(21,201)
Net losses incurred	$ 23,690	$ 33,985	$ 21,836	$ 39,064	$ 27,685	$ (1,518)	$ (13,455)	$ 23,850	$ 118,575	$ 36,562	$ 53,709