Schedule IV Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Premiums Earned									$ 1,074,298	$ 990,016	$ 999,093
Ceded Premiums Earned									67,195	57,271	77,359
Assumed Premiums Earned									6,904	28	35
Net premiums earned—insurance	$ 261,682	$ 258,431	$ 251,344	$ 242,550	$ 245,175	$ 236,702	$ 229,096	$ 221,800	$ 1,014,007	$ 932,773	$ 921,769
SEC Schedule, 12-17, Insurance Companies, Reinsurance, Premium, Percentage Assumed to Net									0.68%	0.00%	0.00%