SEGMENT INFORMATION - Summarized financial information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	$ 149,837	$ 146,446	$ 294,324	$ 289,183
SAP underwriting profit (loss)	(8,674)	(6,263)	(8,021)	6,265
GAAP adjustments	2,477	1,270	1,139	(782)
GAAP underwriting profit (loss)	(6,197)	(4,993)	(6,882)	5,483
Net investment income	11,171	12,179	22,178	24,409
Net realized investment gains (losses)	3,387	1,634	2,760	549
Other income (loss)	(245)	77	(655)	66
Interest expense	85	85	169	169
Other expenses	802	725	1,563	1,374
Income before income tax expense	7,229	8,087	15,669	28,964
Reconciliation of assets from segment to consolidated
Assets	2,185,636		2,185,636		$ 2,131,694
Eliminations	(562,914)		(562,914)		(540,249)
Reclassifications	(325)		(325)		(2,632)
Total assets	1,622,397		1,622,397		1,588,813
Property and casualty insurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	116,187	111,771	229,835	222,217
SAP underwriting profit (loss)	(8,892)	(11,289)	(11,486)	(823)
GAAP adjustments	3,282	1,917	2,275	56
GAAP underwriting profit (loss)	(5,610)	(9,372)	(9,211)	(767)
Net investment income	7,958	8,568	15,973	17,339
Net realized investment gains (losses)	3,738	1,018	3,141	172
Other income (loss)	283	162	444	294
Interest expense	85	85	169	169
Other expenses	231	211	410	368
Income before income tax expense	6,053	80	9,768	16,501
Reconciliation of assets from segment to consolidated
Assets	1,143,680		1,143,680		1,122,037
Eliminations	0		0		0
Reclassifications	(44)		(44)		0
Total assets	1,143,636		1,143,636		1,122,037
Reinsurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	33,650	34,675	64,489	66,966
SAP underwriting profit (loss)	218	5,026	3,465	7,088
GAAP adjustments	(805)	(647)	(1,136)	(838)
GAAP underwriting profit (loss)	(587)	4,379	2,329	6,250
Net investment income	3,201	3,608	6,184	7,065
Net realized investment gains (losses)	(351)	616	(381)	377
Other income (loss)	(528)	(85)	(1,099)	(228)
Interest expense	0	0	0	0
Other expenses	0	0	0	0
Income before income tax expense	1,735	8,518	7,033	13,464
Reconciliation of assets from segment to consolidated
Assets	469,285		469,285		455,493
Eliminations	0		0		0
Reclassifications	0		0		(1,932)
Total assets	469,285		469,285		453,561
Parent company [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	0	0	0	0
SAP underwriting profit (loss)	0	0	0	0
GAAP adjustments	0	0	0	0
GAAP underwriting profit (loss)	0	0	0	0
Net investment income	12	3	21	5
Net realized investment gains (losses)	0	0	0	0
Other income (loss)	0	0	0	0
Interest expense	0	0	0	0
Other expenses	571	514	1,153	1,006
Income before income tax expense	(559)	$ (511)	(1,132)	$ (1,001)
Reconciliation of assets from segment to consolidated
Assets	572,671		572,671		554,164
Eliminations	(562,914)		(562,914)		(540,249)
Reclassifications	(281)		(281)		(700)
Total assets	$ 9,476		$ 9,476		$ 13,215