Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (11,553)	$ 6,526	$ 21,863
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation and amortization expense	4,715	3,894	3,516
Deferred federal income taxes	(1,575)	405	(1,030)
Net realized gains	(5,672)	(2,519)	(5,826)
Share-based payments expense	149	(118)	383
Change in ceded unearned premiums	(30,841)	(16,388)	(11,718)
Change in premiums receivable	(14,658)	(6,339)	(12,373)
Change in accounts receivable	756	(264)	1,136
Change in deferred policy acquisition costs	3,191	1,173	380
Change in unpaid losses and loss adjustment expenses	45,533	30,689	35,743
Change in unearned premiums	35,388	24,847	19,581
Change in reinsurance recoverable	(35,107)	(33,534)	(4,568)
Change in reinsurance balances payable	5,999	12,747	7,338
Change in current federal income tax (recoverable)/payable	(3,581)	(2,172)	(2,747)
Change in all other liabilities	3,091	3,586	(1,368)
Change in all other assets	5,487	5,433	(697)
Net cash provided by operating activities	7,199	30,854	52,936
Cash flows from investing activities:
Purchases of property and equipment, net	(2,705)	(4,340)	(3,608)
Net transfers from restricted cash	4,676	1,195	3,392
Purchases of investment securities	(305,930)	(241,374)	(265,482)
Maturities, sales and redemptions of investment securities	287,187	186,286	169,409
Net cash used in investing activities	(16,772)	(58,233)	(96,289)
Cash flows from financing activities:
Activity under revolving credit facility, net			30,000
Payment of debt issuance costs			(96)
Payment of contingent consideration		(1,784)	(1,216)
Proceeds from exercise of employee stock options	231	466	658
Purchase of treasury shares	(5,308)	(6,117)	(2,532)
Net cash provided by (used in) financing activities	(5,077)	(7,435)	26,814
Decrease in cash and cash equivalents	(14,650)	(34,814)	(16,539)
Cash and cash equivalents at beginning of year	79,632	114,446	130,985
Cash and cash equivalents at end of year	64,982	79,632	114,446
Supplemental cash flow information:
Interest paid	4,506	4,287	3,906
Income taxes paid	137	3,718	13,800
Supplemental schedule of non-cash activities:
Change in receivable for securities related to investment disposals that settled after the balance sheet date	(2,188)	7,377	(9,492)
Change in payable for securities related to investment purchases that settled after the balance sheet date	$ (6,727)	$ 13,118	$ (224)