Financial Schedules Schedule II - Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ (44,204)	$ 3,449	$ 572	$ 2,056	$ 116	$ 2,762	$ 1,482	$ (2,391)	$ (38,127)	$ 1,969	$ (3,143)
Realized investment gains (losses), net									(518)	1,985	5,459
Amortization of premiums and discounts on investments									16,606	14,676	12,021
Depreciation									1,065	806	779
Accrued investment income									(1,159)	(2,497)	(1,949)
Other, net									59	224	(99)
Net cash provided by operating activities									93,012	102,271	87,153
Purchase of fixed maturities, held-to-maturity									0	(5,507)	(55,360)
Purchase of fixed maturities, available-for-sale									(167,699)	(234,964)	(134,126)
Maturities of fixed maturities, available-for-sale									74,902	56,032	75,231
Purchase of equity securities, available-for-sale									0	0	(602)
Sale of other long-term investments and property and equipment									3,041	37	60
Purchase of other long-term investments and property and equipment									0	(75)	0
Purchase of short-term investments									0	(522)	(255)
Maturity of short-term investments									500	256	0
Net cash used in investing activities									(85,005)	(152,077)	(58,034)
Net cash provided by financing activities									2,547	2,489	3,000
Net increase (decrease) in cash and cash equivalents									10,554	(47,317)	32,119
Cash and cash equivalents at beginning of year				35,510				82,827	35,510	82,827	50,708
Cash and cash equivalents at end of year	46,064				35,510				46,064	35,510	82,827
Parent Company [Member]
Net income (loss)									(38,127)	1,969	(3,143)
Equity in income of consolidated subsidiaries									38,745	(1,288)	4,978
Accrued expenses and other liabilities									4,370	(3,018)	483
Amortization of premiums and discounts on investments									714	911	984
Depreciation									319	162	155
Accrued investment income									181	35	(14)
Decrease (increase) in receivable from subsidiaries									(2,901)	300	(627)
Other, net									(102)	149	110
Net cash provided by operating activities									3,199	(780)	2,926
Purchase of fixed maturities, available-for-sale									0	(6,615)	(4,559)
Maturities of fixed maturities, available-for-sale									10,986	8,015	2,645
Sale of other long-term investments and property and equipment									3	371	16
Purchase of other long-term investments and property and equipment									(261)	(740)	(88)
Purchase of short-term investments									0	(522)	0
Maturity of short-term investments									500	0	0
Capital contribution to subsidiary									(5,250)	0	0
Net cash used in investing activities									5,978	509	(1,986)
Purchase of the Company's stock from affiliates									0	(812)	0
Net cash provided by financing activities									0	(812)	0
Net increase (decrease) in cash and cash equivalents									9,177	(1,083)	940
Cash and cash equivalents at beginning of year				$ 14,673				$ 15,756	14,673	15,756	14,816
Cash and cash equivalents at end of year	$ 23,850				$ 14,673				$ 23,850	$ 14,673	$ 15,756