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
SCHEDULE IV -- REINSURANCE [Abstract]
Direct premiums	[1]									$ 562,364		$ 470,158		$ 394,679
Ceded to other companies	[1]									131,080		145,201		130,012
Assumed from other companies	[1]									1,596		3,188		11,344
Net		$ 118,671	$ 96,807	$ 111,940	$ 105,462	$ 97,075	$ 89,100	$ 67,996	$ 73,974	$ 432,880	[1]	$ 328,145	[1]	$ 276,011	[1]
% of amount assumed to net	[1]									0.40%		1.00%		4.10%
Retrocessions associated with premiums assumed from other companies										$ 0		$ 0		$ 86

[1] Included in Ceded to Other Companies is $0, $0 and $86 for 2018, 2017 and 2016, respectively, relating to retrocessions associated with premiums assumed from other companies. percentage of Amount Assumed to Net above considers the impact of this retrocession.