SEGMENT INFORMATION - Summarized financial information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	$ 152,181	$ 145,788	$ 441,364	$ 429,124
SAP underwriting profit (loss)	(7,392)	(4,654)	(1,127)	4,188
GAAP adjustments	3,005	2,018	2,223	8,667
GAAP underwriting profit (loss)	(4,387)	(2,636)	1,096	12,855
Net investment income (loss)	11,474	11,299	35,883	33,946
Net realized investment gains (losses)	(1,192)	7,498	(643)	11,555
Other income (loss)	(85)	519	(19)	1,622
Interest expense	84	84	253	253
Other expenses	679	675	2,053	1,992
Income before income tax expense	5,047	15,921	34,011	57,733
Reconciliation of assets from segment to consolidated
Assets	2,198,376		2,198,376		$ 2,055,437
Eliminations	(554,093)		(554,093)		(514,309)
Reclassifications	(6,778)		(6,778)		(5,173)
Total assets	1,637,505		1,637,505		1,535,955
Property and casualty insurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	116,372	113,753	338,589	333,212
SAP underwriting profit (loss)	(8,081)	(2,487)	(8,904)	(497)
GAAP adjustments	2,970	2,386	3,026	7,962
GAAP underwriting profit (loss)	(5,111)	(101)	(5,878)	7,465
Net investment income (loss)	8,185	8,125	25,524	24,301
Net realized investment gains (losses)	(799)	4,889	(627)	7,866
Other income (loss)	172	210	466	582
Interest expense	84	84	253	253
Other expenses	190	196	558	568
Income before income tax expense	2,173	12,843	18,674	39,393
Reconciliation of assets from segment to consolidated
Assets	1,170,108		1,170,108		1,092,820
Eliminations	0		0		0
Reclassifications	(2,187)		(2,187)		0
Total assets	1,167,921		1,167,921		1,092,820
Reinsurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	35,809	32,035	102,775	95,912
SAP underwriting profit (loss)	689	(2,167)	7,777	4,685
GAAP adjustments	35	(368)	(803)	705
GAAP underwriting profit (loss)	724	(2,535)	6,974	5,390
Net investment income (loss)	3,285	3,176	10,350	9,654
Net realized investment gains (losses)	(393)	2,609	(16)	3,689
Other income (loss)	(257)	309	(485)	1,040
Interest expense	0	0	0	0
Other expenses	0	0	0	0
Income before income tax expense	3,359	3,559	16,823	19,773
Reconciliation of assets from segment to consolidated
Assets	465,733		465,733		437,575
Eliminations	0		0		0
Reclassifications	(3,426)		(3,426)		(5,173)
Total assets	462,307		462,307		432,402
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 (loss)	4	(2)	9	(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	489	479	1,495	1,424
Income before income tax expense	(485)	$ (481)	(1,486)	$ (1,433)
Reconciliation of assets from segment to consolidated
Assets	562,535		562,535		525,042
Eliminations	(554,093)		(554,093)		(514,309)
Reclassifications	(1,165)		(1,165)		0
Total assets	$ 7,277		$ 7,277		$ 10,733