Investments (Details 3) $ in Thousands	Jun. 30, 2017 USD ($) Holdings	Dec. 31, 2016 USD ($) Holdings
Fair value
Less than 12 months	$ 251,209	$ 269,475
12 months or longer	20,170	22,193
Total	271,379	291,668
Unrealized losses
Less than 12 months	2,194	4,116
12 months or longer	816	1,047
Total	$ 3,010	$ 5,163
No. of holdings | Holdings	286	253
Investment grade
Fair value
Less than 12 months	$ 206,737	$ 239,041
12 months or longer	16,636	16,061
Total	223,373	255,102
Unrealized losses
Less than 12 months	1,487	3,605
12 months or longer	325	399
Total	$ 1,812	$ 4,004
No. of holdings | Holdings	124	136
Non-investment grade
Fair value
Less than 12 months	$ 44,472	$ 24,484
12 months or longer	3,534	6,132
Total	48,006	30,616
Unrealized losses
Less than 12 months	707	309
12 months or longer	491	648
Total	$ 1,198	$ 957
No. of holdings | Holdings	162	116
Fixed maturities
Fair value
Less than 12 months	$ 251,209	$ 263,525
12 months or longer	20,170	22,193
Total	271,379	285,718
Unrealized losses
Less than 12 months	2,194	3,914
12 months or longer	816	1,047
Total	$ 3,010	$ 4,961
No. of holdings | Holdings	286	252
U.S. treasury
Fair value
Less than 12 months	$ 5,051	$ 5,031
12 months or longer	0	0
Total	5,051	5,031
Unrealized losses
Less than 12 months	31	62
12 months or longer	0	0
Total	$ 31	$ 62
No. of holdings | Holdings	1	1
States & political subdivisions
Fair value
Less than 12 months	$ 50,085	$ 84,611
12 months or longer	1,123	0
Total	51,208	84,611
Unrealized losses
Less than 12 months	721	2,293
12 months or longer	37	0
Total	$ 758	$ 2,293
No. of holdings | Holdings	24	40
Corporate debt securities
Fair value
Less than 12 months	$ 143,284	$ 112,453
12 months or longer	6,228	8,692
Total	149,512	121,145
Unrealized losses
Less than 12 months	1,059	987
12 months or longer	225	399
Total	$ 1,284	$ 1,386
No. of holdings | Holdings	211	155
Residential mortgage-backed securities
Fair value
Less than 12 months	$ 4,489	$ 7,451
12 months or longer	4,097	4,974
Total	8,586	12,425
Unrealized losses
Less than 12 months	56	60
12 months or longer	90	131
Total	$ 146	$ 191
No. of holdings | Holdings	8	13
Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 19,545	$ 26,509
12 months or longer	7,702	4,319
Total	27,247	30,828
Unrealized losses
Less than 12 months	292	437
12 months or longer	461	496
Total	$ 753	$ 933
No. of holdings | Holdings	26	28
Collateralized debt obligations
Fair value
Less than 12 months	$ 28,755	$ 27,470
12 months or longer	1,020	4,208
Total	29,775	31,678
Unrealized losses
Less than 12 months	35	75
12 months or longer	3	21
Total	$ 38	$ 96
No. of holdings | Holdings	16	15
Common stock
Fair value
Less than 12 months		$ 5,950
12 months or longer		0
Total		5,950
Unrealized losses
Less than 12 months		202
12 months or longer		0
Total		$ 202
No. of holdings | Holdings		1