Investments, Available-for-sale Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fixed maturities [Abstract]
Amortized cost	$ 422,255	$ 413,526
Estimated fair value	425,191	411,223
Equity securities [Abstract]
Amortized cost	45,916	14,350
Estimated fair value	54,132	18,374
Total available-for-sale investments [Abstract]
Amortized cost	468,171	427,876
Gross unrealized holding gains	13,627	6,880
Gross unrealized holding losses	(2,475)	(5,159)
Estimated fair value	479,323	429,597
Fixed Maturities [Member]
Fixed maturities [Abstract]
Amortized cost	422,255	413,526
Gross unrealized holding gains	5,180	2,854
Gross unrealized holding losses	(2,244)	(5,157)
Estimated fair value	425,191	411,223
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Fixed maturities [Abstract]
Amortized cost	9,108	12,106
Gross unrealized holding gains	4	8
Gross unrealized holding losses	(14)	(16)
Estimated fair value	9,098	12,098
Obligations of States, Municipalities and Political Subdivisions [Member]
Fixed maturities [Abstract]
Amortized cost	161,012	124,728
Gross unrealized holding gains	3,726	1,470
Gross unrealized holding losses	(412)	(2,960)
Estimated fair value	164,326	123,238
Corporate and Other Securities [Member]
Fixed maturities [Abstract]
Amortized cost	71,224	118,473
Gross unrealized holding gains	579	550
Gross unrealized holding losses	(172)	(233)
Estimated fair value	71,631	118,790
Asset-backed Securities [Member]
Fixed maturities [Abstract]
Amortized cost	95,223	73,317
Gross unrealized holding gains	405	241
Gross unrealized holding losses	(268)	(264)
Estimated fair value	95,360	73,294
Residential Mortgage-backed Securities [Member]
Fixed maturities [Abstract]
Amortized cost	85,688	84,902
Gross unrealized holding gains	466	585
Gross unrealized holding losses	(1,378)	(1,684)
Estimated fair value	84,776	83,803
Equity Securities [Member]
Equity securities [Abstract]
Amortized cost	45,916
Gross unrealized holding gains	8,447
Gross unrealized holding losses	(231)
Estimated fair value	54,132
Exchange Traded Fund [Member]
Equity securities [Abstract]
Amortized cost	26,041	14,350
Gross unrealized holding gains	8,339	4,026
Gross unrealized holding losses	0	(2)
Estimated fair value	34,380	$ 18,374
Nonredeemable Preferred Stock [Member]
Equity securities [Abstract]
Amortized cost	19,875
Gross unrealized holding gains	108
Gross unrealized holding losses	(231)
Estimated fair value	$ 19,752

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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