Segment Information - Information by Reportable Segment (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	Dec. 31, 2013
Segment Reporting Information [Line Items]
Gross premiums written	$ 31,308	$ 28,497	$ 29,725	$ 25,393	$ 25,245	$ 24,242	$ 23,059	$ 21,204
Net written premiums	27,069	24,634	26,176	22,050	21,467	28,599	15,942	13,666	$ 99,929	$ 79,674	$ 66,299
Net earned premiums	24,463	23,380	21,675	20,109	19,274	17,883	15,115	14,493	89,627	66,765	57,528
Other income	287	303	283	245	175	523	480	489	1,118	1,667	1,809
Total revenue									93,883	70,723	60,929
Losses and loss adjustment expenses, net	18,181	14,582	13,541	12,699	11,523	9,813	8,976	8,570	59,003	38,882	40,730
Policy acquisition costs	6,997	6,266	6,014	6,003	6,344	4,605	2,639	2,595	25,280	16,183	14,696
Operating expenses	4,211	4,710	4,536	4,139	4,170	3,325	3,619	3,692	17,596	14,806	12,139
Total expenses									102,526	70,640	68,149
Income (loss) before income taxes									(8,643)	83	(7,220)
Investment income	548	560	528	537	442	505	469	486	2,173	1,902	1,175
Net realized investment gains	761	71	541	(8)	47	6	87	145	1,365	285	417
Other gains (losses)	(400)	0	0	0	0	104	0	0	(400)	104	0
Interest expense	(179)	$ (168)	$ (143)	$ (157)	(105)	$ (181)	$ (239)	$ (244)	(647)	(769)	(584)
Deferred policy acquisition costs	13,290				12,102				13,290	12,102	5,679	$ 5,747
Unearned premiums	58,126				47,916				58,126	47,916	43,381
Loss and loss adjustment expense reserves	54,651				35,422				54,651	35,422	31,531	$ 28,908
Commercial Lines [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	10,156				8,401				10,156	8,401	4,247
Unearned premiums	44,484				33,337				44,484	33,337	29,062
Loss and loss adjustment expense reserves	46,917				29,739				46,917	29,739	22,451
Personal Lines [Member]
Segment Reporting Information [Line Items]
Deferred policy acquisition costs	3,134				3,701				3,134	3,701	1,432
Unearned premiums	13,642				14,579				13,642	14,579	14,319
Loss and loss adjustment expense reserves	$ 7,734				$ 5,683				7,734	5,683	9,080
Operating Segments [Member] | Commercial Lines [Member]
Segment Reporting Information [Line Items]
Gross premiums written									88,242	68,197	55,056
Net written premiums									78,439	58,157	40,958
Net earned premiums									68,921	48,586	35,749
Other income									378	1,099	918
Total revenue									69,299	49,685	36,667
Losses and loss adjustment expenses, net									42,441	25,730	20,621
Policy acquisition costs									18,560	11,937	9,209
Operating expenses									6,767	4,983	4,566
Total expenses									67,768	42,650	34,396
Income (loss) before income taxes									1,531	7,035	2,271
Operating Segments [Member] | Personal Lines [Member]
Segment Reporting Information [Line Items]
Gross premiums written									26,681	25,553	28,791
Net written premiums									21,490	21,517	25,341
Net earned premiums									20,706	18,179	21,779
Other income									558	489	904
Total revenue									21,264	18,668	22,683
Losses and loss adjustment expenses, net									16,562	13,152	20,109
Policy acquisition costs									6,720	4,246	5,487
Operating expenses									2,911	3,305	2,453
Total expenses									26,193	20,703	28,049
Income (loss) before income taxes									(4,929)	(2,035)	(5,366)
Corporate [Member]
Segment Reporting Information [Line Items]
Gross premiums written									0	0	0
Net written premiums									0	0	0
Net earned premiums									0	0	0
Other income									182	79	(13)
Total revenue									182	79	(13)
Losses and loss adjustment expenses, net									0	0	0
Policy acquisition costs									0	0	0
Operating expenses									7,918	6,518	5,120
Total expenses									7,918	6,518	5,120
Income (loss) before income taxes									(7,736)	(6,439)	(5,133)
Operating Segments and Corporate Non Segment [Member]
Segment Reporting Information [Line Items]
Gross premiums written									114,923	93,750	83,847
Net written premiums									99,929	79,674	66,299
Net earned premiums									89,627	66,765	57,528
Other income									1,118	1,667	1,809
Total revenue									90,745	68,432	59,337
Losses and loss adjustment expenses, net									59,003	38,882	40,730
Policy acquisition costs									25,280	16,183	14,696
Operating expenses									17,596	14,806	12,139
Total expenses									101,879	69,871	67,565
Income (loss) before income taxes									(11,134)	(1,439)	(8,228)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment income									2,173	1,902	1,175
Net realized investment gains									1,365	285	417
Other gains (losses)									(400)	104
Interest expense									(647)	(769)	(584)
Corporate And Reconciling Items [Member]
Segment Reporting Information [Line Items]
Income (loss) before income taxes									$ (5,245)	$ (4,917)	$ (4,125)