SEGMENT INFORMATION - Summarized financial information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	$ 155,190	$ 152,181	$ 449,514	$ 441,364
SAP underwriting profit (loss)	(16,437)	(7,392)	(24,458)	(1,127)
GAAP adjustments	6,054	3,005	7,193	2,223
GAAP underwriting profit (loss)	(10,383)	(4,387)	(17,265)	1,096
Net investment income	11,501	11,474	33,679	35,883
Net realized investment gains (losses)	(594)	(1,192)	2,166	(643)
Other income (loss)	(179)	(85)	(834)	(19)
Interest expense	84	84	253	253
Other expenses	701	679	2,264	2,053
Income (loss) before income tax expense (benefit)	(440)	5,047	15,229	34,011
Reconciliation of assets from segment to consolidated
Assets	2,242,585		2,242,585		$ 2,131,694
Eliminations	(568,814)		(568,814)		(540,249)
Reclassifications	(2,933)		(2,933)		(2,632)
Total assets	1,670,838		1,670,838		1,588,813
Property and casualty insurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	120,472	116,372	350,307	338,589
SAP underwriting profit (loss)	1,927	(8,081)	(9,559)	(8,904)
GAAP adjustments	5,860	2,970	8,135	3,026
GAAP underwriting profit (loss)	7,787	(5,111)	(1,424)	(5,878)
Net investment income	8,252	8,185	24,225	25,524
Net realized investment gains (losses)	(108)	(799)	3,033	(627)
Other income (loss)	179	172	623	466
Interest expense	84	84	253	253
Other expenses	170	190	580	558
Income (loss) before income tax expense (benefit)	15,856	2,173	25,624	18,674
Reconciliation of assets from segment to consolidated
Assets	1,185,269		1,185,269		1,122,037
Eliminations	0		0		0
Reclassifications	(2,772)		(2,772)		0
Total assets	1,182,497		1,182,497		1,122,037
Reinsurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	34,718	35,809	99,207	102,775
SAP underwriting profit (loss)	(18,364)	689	(14,899)	7,777
GAAP adjustments	194	35	(942)	(803)
GAAP underwriting profit (loss)	(18,170)	724	(15,841)	6,974
Net investment income	3,237	3,285	9,421	10,350
Net realized investment gains (losses)	(486)	(393)	(867)	(16)
Other income (loss)	(358)	(257)	(1,457)	(485)
Interest expense	0	0	0	0
Other expenses	0	0	0	0
Income (loss) before income tax expense (benefit)	(15,777)	3,359	(8,744)	16,823
Reconciliation of assets from segment to consolidated
Assets	481,951		481,951		455,493
Eliminations	0		0		0
Reclassifications	0		0		(1,932)
Total assets	481,951		481,951		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	4	33	9
Net realized investment gains (losses)	0	0	0	0
Other income (loss)	0	0	0	0
Interest expense	0	0	0	0
Other expenses	531	489	1,684	1,495
Income (loss) before income tax expense (benefit)	(519)	$ (485)	(1,651)	$ (1,486)
Reconciliation of assets from segment to consolidated
Assets	575,365		575,365		554,164
Eliminations	(568,814)		(568,814)		(540,249)
Reclassifications	(161)		(161)		(700)
Total assets	$ 6,390		$ 6,390		$ 13,215