REINSURANCE (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) reinsurer	Dec. 31, 2014 USD ($) reinsurer	Dec. 31, 2013 USD ($)
Reinsurance Transactions For Insurance Companies, by Product Segment [Line Items]
Number of significant nonaffiliated reinsurers | reinsurer	3	3
Total receivable amount from significant nonaffiliated reinsurers	$ 12,700	$ 16,300
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Premiums written
Net premiums written	$ 578,938	$ 552,610	$ 534,077
Premiums earned
Direct	366,752	372,658	361,010
Assumed	611,045	591,666	567,918
Ceded	(407,531)	(423,602)	(413,422)
Net premiums earned	570,266	540,722	515,506
Losses and settlement expenses incurred
Net losses and settlement expenses incurred	370,736	385,474	333,287
Affiliated Entity [Member]
Premiums written
Assumed	474,323	455,183	425,218
Ceded	(381,782)	(378,071)	(381,293)
Premiums earned
Assumed	466,966	443,440	412,665
Ceded	(377,579)	(382,997)	(373,771)
Losses and settlement expenses incurred
Assumed	295,181	305,857	268,491
Ceded	(199,126)	(226,662)	(237,932)
Non Affiliated Entity [Member]
Premiums written
Direct	370,955	367,732	368,532
Assumed	143,092	147,519	165,792
Ceded	(27,650)	(39,753)	(44,172)
Premiums earned
Direct	366,752	372,658	361,010
Assumed	144,079	148,226	155,253
Ceded	(29,952)	(40,605)	(39,651)
Losses and settlement expenses incurred
Direct	198,504	227,382	237,109
Assumed	85,922	98,482	83,135
Ceded	$ (9,745)	$ (19,585)	$ (17,516)
Property and casualty insurance [Member]
Reinsurance Transactions For Insurance Companies, by Product Segment [Line Items]
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Premiums written
Net premiums written	$ 454,434	$ 433,707	$ 405,049
Premiums earned
Net premiums earned	447,197	422,381	392,719
Losses and settlement expenses incurred
Net losses and settlement expenses incurred	$ 291,883	$ 298,033	$ 260,917
Property and casualty insurance [Member] | Affiliated Entity [Member]
Reinsurance Transactions For Insurance Companies, by Product Segment [Line Items]
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Premiums written
Assumed	$ 474,323	$ 455,183	$ 425,218
Ceded	(370,955)	(367,732)	(368,532)
Premiums earned
Assumed	466,966	443,440	412,665
Ceded	(366,752)	(372,658)	(361,010)
Losses and settlement expenses incurred
Assumed	294,324	304,579	267,292
Ceded	(198,504)	(227,382)	(237,109)
Property and casualty insurance [Member] | Non Affiliated Entity [Member]
Premiums written
Direct	370,955	367,732	368,532
Assumed	4,392	3,955	3,501
Ceded	(24,281)	(25,431)	(23,670)
Premiums earned
Direct	366,752	372,658	361,010
Assumed	4,240	3,787	3,275
Ceded	(24,009)	(24,846)	(23,221)
Losses and settlement expenses incurred
Direct	198,504	227,382	237,109
Assumed	2,407	2,201	2,281
Ceded	(4,848)	(8,747)	(8,656)
Reinsurance [Member]
Premiums written
Net premiums written	124,504	118,903	129,028
Premiums earned
Net premiums earned	123,069	118,341	122,787
Losses and settlement expenses incurred
Net losses and settlement expenses incurred	78,853	87,441	72,370
Reinsurance [Member] | Affiliated Entity [Member]
Premiums written
Assumed	0	0	0
Ceded	(10,827)	(10,339)	(12,761)
Premiums earned
Assumed	0	0	0
Ceded	(10,827)	(10,339)	(12,761)
Losses and settlement expenses incurred
Assumed	857	1,278	1,199
Ceded	(622)	720	(823)
Reinsurance [Member] | Non Affiliated Entity [Member]
Premiums written
Direct	0	0	0
Assumed	138,700	143,564	162,291
Ceded	(3,369)	(14,322)	(20,502)
Premiums earned
Direct	0	0	0
Assumed	139,839	144,439	151,978
Ceded	(5,943)	(15,759)	(16,430)
Losses and settlement expenses incurred
Direct	0	0	0
Assumed	83,515	96,281	80,854
Ceded	$ (4,897)	$ (10,838)	$ (8,860)