Reinsurance - Summary of Quota Share Reinsurance Agreements (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jul. 01, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premiums Earned, Net [Abstract]
Premiums earned, direct										$ 1,058,545	$ 997,892	$ 950,973
Premiums earned, assumed										662	1,178	1,653
Premiums earned, ceded										(133,981)	(102,848)	(108,255)
Net premiums earned		$ 235,053	$ 237,376	$ 231,456	$ 221,341	$ 226,192	$ 239,234	$ 213,508	$ 217,288	925,226	896,222	844,371
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, direct										273,207	369,680	524,051
Losses incurred, assumed										1,138	1,552	2,012
Losses incurred, ceded										(34,188)	(27,685)	(29,986)
Net losses incurred		$ 47,658	$ 60,897	$ 46,590	$ 85,012	$ 95,066	76,458	$ 90,238	$ 81,785	240,157	343,547	496,077
Ceded premiums written, net of profit commission										133,885	55,391	119,634
Ceded premiums earned, net of profit commission										133,981	102,848	108,255
Ceded losses incurred										34,188	27,685	29,986
Quota Share Reinsurance Agreement, 2015
Premiums Earned, Net [Abstract]
Premiums earned, ceded										(125,460)	(52,588)
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, ceded										(30,201)	(11,424)
Ceded premiums written, net of profit commission										125,460	52,588
Ceded premiums earned, net of profit commission										125,460	52,588
Ceded losses incurred										30,201	11,424
Ceding commission										47,629	20,582
Profit commission										$ 112,685	50,322
Quota Share Reinsurance Agreement, 2013
Premiums Earned, Net [Abstract]
Premiums earned, ceded							(11,600)				(35,999)	(88,528)
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, ceded											(6,060)	(15,163)
Ceded premiums written, net of profit commission							69,400				(11,355)	100,031
Ceded premiums earned, net of profit commission							11,600				35,999	88,528
Ceded losses incurred											6,060	15,163
Ceding commission							$ 11,600				10,235	37,833
Profit commission	$ 142,500										$ 62,525	$ 89,133