Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale securities
Amortized cost, fixed maturities	$ 740,809
Amortized cost	740,809	$ 708,555
Gross unrealized gains	10,737	9,899
Gross unrealized losses	2,280	5,163
Estimated fair value, fixed maturities	749,266
Estimated fair value	749,266	713,291
Fixed maturities
Available-for-sale securities
Amortized cost, fixed maturities	740,809	702,403
Gross unrealized gains, fixed maturities	10,737	9,899
Gross unrealized losses, fixed maturities	2,280	4,961
Estimated fair value, fixed maturities	749,266	707,341
U.S. treasury
Available-for-sale securities
Amortized cost, fixed maturities	11,878	5,093
Gross unrealized gains, fixed maturities	0	0
Gross unrealized losses, fixed maturities	44	62
Estimated fair value, fixed maturities	11,834	5,031
Government sponsored entities
Available-for-sale securities
Amortized cost, fixed maturities		2,004
Gross unrealized gains, fixed maturities		22
Gross unrealized losses, fixed maturities		0
Estimated fair value, fixed maturities		2,026
States & political subdivisions
Available-for-sale securities
Amortized cost, fixed maturities	254,835	249,312
Gross unrealized gains, fixed maturities	7,809	6,113
Gross unrealized losses, fixed maturities	678	2,293
Estimated fair value, fixed maturities	261,966	253,132
Foreign government securities
Available-for-sale securities
Amortized cost, fixed maturities	501
Gross unrealized gains, fixed maturities	6
Gross unrealized losses, fixed maturities	0
Estimated fair value, fixed maturities	507
Corporate debt securities
Available-for-sale securities
Amortized cost, fixed maturities	345,003	321,041
Gross unrealized gains, fixed maturities	2,201	3,293
Gross unrealized losses, fixed maturities	832	1,386
Estimated fair value, fixed maturities	346,372	322,948
Residential mortgage-backed securities
Available-for-sale securities
Amortized cost, fixed maturities	25,388	16,232
Gross unrealized gains, fixed maturities	404	61
Gross unrealized losses, fixed maturities	73	191
Estimated fair value, fixed maturities	25,719	16,102
Commercial mortgage-backed securities
Available-for-sale securities
Amortized cost, fixed maturities	34,892	37,723
Gross unrealized gains, fixed maturities	73	59
Gross unrealized losses, fixed maturities	634	933
Estimated fair value, fixed maturities	34,331	36,849
Collateralized debt obligations
Available-for-sale securities
Amortized cost, fixed maturities	62,193	68,998
Gross unrealized gains, fixed maturities	207	351
Gross unrealized losses, fixed maturities	19	96
Estimated fair value, fixed maturities	62,381	69,253
Other debt securities
Available-for-sale securities
Amortized cost, fixed maturities	6,119	2,000
Gross unrealized gains, fixed maturities	37	0
Gross unrealized losses, fixed maturities	0	0
Estimated fair value, fixed maturities	$ 6,156	2,000
Common stock
Available-for-sale securities
Amortized cost, equity securities		6,152
Gross unrealized gains, equity securities		0
Gross unrealized losses, equity securities		202
Estimated fair value, equity securities		$ 5,950

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