SCHEDULE IV - REINSURANCE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	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
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums									$ 394,679	$ 370,499	$ 342,656
Ceded to Other Companies									86	562	1,275
Assumed from Other Companies									11,344	21,533	38,219
Net	$ 69,141	$ 71,235	$ 68,726	$ 66,909	$ 65,995	$ 65,445	$ 65,449	$ 66,446	276,011	263,335	261,627
Retrocessions associated with premiums assumed from other companies									86	562	1,275
Property and Casualty Insurance [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums									394,679	370,499	342,656
Ceded to Other Companies									130,012	128,697	119,248
Assumed from Other Companies									11,344	21,533	38,219
Net									$ 276,011	$ 263,335	$ 261,627
% of Amount Assumed to Net									4.10%	8.00%	14.10%