Investments - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities:
Fixed maturity securities, amortized cost	$ 129,322	$ 137,004
Fixed maturity securities, gross unrealized gain	224	531
Fixed maturity securities, gross unrealized loss	(2,869)	(999)
Fixed maturity securities	126,677	136,536
Equity Securities
Equity securities, amortized cost	8,782	8,629
Equity securities, gross unrealized gain		1,240
Equity securities, gross unrealized loss		(182)
Equity securities, estimated fair value	9,530	9,687
Securities, cost or amortized cost		145,633
Securities, gross unrealized gain		1,771
Securities, gross unrealized loss		(1,181)
Securities, estimated fair value		146,223
U.S. Government
Debt Securities:
Fixed maturity securities, amortized cost	16,007	17,179
Fixed maturity securities, gross unrealized gain	2	10
Fixed maturity securities, gross unrealized loss	(266)	(99)
Fixed maturity securities	15,743	17,090
State and local government
Debt Securities:
Fixed maturity securities, amortized cost	16,536	17,302
Fixed maturity securities, gross unrealized gain	96	255
Fixed maturity securities, gross unrealized loss	(221)	(54)
Fixed maturity securities	16,411	17,503
Corporate debt
Debt Securities:
Fixed maturity securities, amortized cost	32,201	38,947
Fixed maturity securities, gross unrealized gain	79	170
Fixed maturity securities, gross unrealized loss	(739)	(209)
Fixed maturity securities	31,541	38,908
Asset-backed securities
Debt Securities:
Fixed maturity securities, amortized cost	25,780	23,539
Fixed maturity securities, gross unrealized gain	27	36
Fixed maturity securities, gross unrealized loss	(153)	(35)
Fixed maturity securities	25,654	23,540
Mortgage-backed securities
Debt Securities:
Fixed maturity securities, amortized cost	32,554	33,942
Fixed maturity securities, gross unrealized gain	11	38
Fixed maturity securities, gross unrealized loss	(1,331)	(522)
Fixed maturity securities	31,234	33,458
Commercial mortgage-backed securities
Debt Securities:
Fixed maturity securities, amortized cost	3,916	3,532
Fixed maturity securities, gross unrealized gain	0	3
Fixed maturity securities, gross unrealized loss	(96)	(44)
Fixed maturity securities	3,820	3,491
Collateralized mortgage obligations
Debt Securities:
Fixed maturity securities, amortized cost	2,328	2,563
Fixed maturity securities, gross unrealized gain	9	19
Fixed maturity securities, gross unrealized loss	(63)	(36)
Fixed maturity securities	$ 2,274	$ 2,546

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