Investments (Details 3) $ in Thousands	Dec. 31, 2016 USD ($) Holdings	Dec. 31, 2015 USD ($) Holdings
Fair value
Less than 12 months	$ 269,475	$ 244,279
12 months or longer	22,193	48,518
Total	291,668	292,797
Unrealized losses
Less than 12 months	4,116	2,882
12 months or longer	1,047	3,151
Total	$ 5,163	$ 6,033
No. of holdings | Holdings	253	407
Investment grade
Fair value
Less than 12 months	$ 239,041	$ 174,723
12 months or longer	16,061	38,369
Total	255,102	213,092
Unrealized losses
Less than 12 months	3,605	1,296
12 months or longer	399	1,256
Total	$ 4,004	$ 2,552
No. of holdings | Holdings	136	105
Non-investment grade
Fair value
Less than 12 months	$ 24,484	$ 56,824
12 months or longer	6,132	10,149
Total	30,616	66,973
Unrealized losses
Less than 12 months	309	1,453
12 months or longer	648	1,895
Total	$ 957	$ 3,348
No. of holdings | Holdings	116	301
Fixed maturities
Fair value
Less than 12 months	$ 263,525	$ 231,547
12 months or longer	22,193	48,518
Total	285,718	280,065
Unrealized losses
Less than 12 months	3,914	2,749
12 months or longer	1,047	3,151
Total	$ 4,961	$ 5,900
No. of holdings | Holdings	252	406
U.S. treasury
Fair value
Less than 12 months	$ 5,031
12 months or longer	0
Total	5,031
Unrealized losses
Less than 12 months	62
12 months or longer	0
Total	$ 62
No. of holdings | Holdings	1
States & political subdivisions
Fair value
Less than 12 months	$ 84,611	$ 5,867
12 months or longer	0	0
Total	84,611	5,867
Unrealized losses
Less than 12 months	2,293	7
12 months or longer	0	0
Total	$ 2,293	$ 7
No. of holdings | Holdings	40	3
Corporate debt securities
Fair value
Less than 12 months	$ 112,453	$ 172,831
12 months or longer	8,692	19,086
Total	121,145	191,917
Unrealized losses
Less than 12 months	987	2,447
12 months or longer	399	1,965
Total	$ 1,386	$ 4,412
No. of holdings | Holdings	155	349
Residential mortgage-backed securities
Fair value
Less than 12 months	$ 7,451	$ 9,827
12 months or longer	4,974	936
Total	12,425	10,763
Unrealized losses
Less than 12 months	60	84
12 months or longer	131	46
Total	$ 191	$ 130
No. of holdings | Holdings	13	9
Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 26,509	$ 13,081
12 months or longer	4,319	19,081
Total	30,828	32,162
Unrealized losses
Less than 12 months	437	68
12 months or longer	496	1,021
Total	$ 933	$ 1,089
No. of holdings | Holdings	28	24
Collateralized debt obligations
Fair value
Less than 12 months	$ 27,470	$ 27,981
12 months or longer	4,208	9,174
Total	31,678	37,155
Unrealized losses
Less than 12 months	75	103
12 months or longer	21	118
Total	$ 96	$ 221
No. of holdings | Holdings	15	19
Other debt securities
Fair value
Less than 12 months		$ 1,960
12 months or longer		241
Total		2,201
Unrealized losses
Less than 12 months		40
12 months or longer		1
Total		$ 41
No. of holdings | Holdings		2
Common stock
Fair value
Less than 12 months	$ 5,950	$ 12,732
12 months or longer	0	0
Total	5,950	12,732
Unrealized losses
Less than 12 months	202	133
12 months or longer	0	0
Total	$ 202	$ 133
No. of holdings | Holdings	1	1