Investments - Investments by major category (Details) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
$ 1,512,939
|
$ 1,439,878
|
| Fixed maturities, Fair Value |
1,497,930
|
1,441,107
|
| Equity Securities |
|
|
| Equity securities, Amortized cost |
65,913
|
68,812
|
| Equity securities, Fair Value |
90,498
|
96,004
|
| Available-for-sale securities, Amortized Cost or Cost, Total |
1,512,939
|
1,511,232
|
| Available-for-sale securities, Gross Unrealized Gains |
3,612
|
36,463
|
| Available-for-sale securities, Gross Unrealized Losses |
(18,621)
|
(8,042)
|
| Available-for-sale securities, Fair Value |
1,497,930
|
1,539,653
|
| Available-for-sale securities, OTTI Recognized in Accumulated OCI |
(72)
|
(1,564)
|
| Fixed Maturities |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
1,512,939
|
1,439,878
|
| Fixed maturities, Gross Unrealized Gains |
3,612
|
9,271
|
| Fixed maturities, Gross Unrealized Losses |
(18,621)
|
(8,042)
|
| Fixed maturities, Fair Value |
1,497,930
|
1,441,107
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
(72)
|
(1,564)
|
| U.S. government |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
125,887
|
61,196
|
| Fixed maturities, Gross Unrealized Gains |
58
|
0
|
| Fixed maturities, Gross Unrealized Losses |
(1,188)
|
(668)
|
| Fixed maturities, Fair Value |
124,757
|
60,528
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
0
|
0
|
| State and Municipal |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
297,994
|
492,442
|
| Fixed maturities, Gross Unrealized Gains |
1,031
|
2,768
|
| Fixed maturities, Gross Unrealized Losses |
(2,211)
|
(999)
|
| Fixed maturities, Fair Value |
296,814
|
494,211
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
0
|
(46)
|
| Mortgage- Backed Securities |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
435,372
|
384,481
|
| Fixed maturities, Gross Unrealized Gains |
693
|
1,830
|
| Fixed maturities, Gross Unrealized Losses |
(8,996)
|
(4,750)
|
| Fixed maturities, Fair Value |
427,068
|
381,561
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
(72)
|
(1,479)
|
| Residential |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
372,319
|
353,277
|
| Fixed maturities, Gross Unrealized Gains |
669
|
1,812
|
| Fixed maturities, Gross Unrealized Losses |
(7,981)
|
(4,097)
|
| Fixed maturities, Fair Value |
365,007
|
350,992
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
(72)
|
(1,479)
|
| Commercial |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
63,053
|
31,204
|
| Fixed maturities, Gross Unrealized Gains |
23
|
18
|
| Fixed maturities, Gross Unrealized Losses |
(1,016)
|
(653)
|
| Fixed maturities, Fair Value |
62,061
|
30,569
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
0
|
0
|
| Asset-backed securities |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
129,010
|
62,552
|
| Fixed maturities, Gross Unrealized Gains |
104
|
62
|
| Fixed maturities, Gross Unrealized Losses |
(630)
|
(196)
|
| Fixed maturities, Fair Value |
128,484
|
62,418
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
0
|
(8)
|
| Corporates |
|
|
| Fixed Maturities |
|
|
| Amortized Cost, Fixed Maturities |
524,676
|
439,208
|
| Fixed maturities, Gross Unrealized Gains |
1,726
|
4,610
|
| Fixed maturities, Gross Unrealized Losses |
(5,595)
|
(1,429)
|
| Fixed maturities, Fair Value |
520,807
|
442,390
|
| Fixed maturities, OTTI Recognized in Accumulated OCI |
0
|
(31)
|
| Equity securities |
|
|
| Equity Securities |
|
|
| Equity securities, Amortized cost |
|
68,812
|
| Equity securities, Gross Unrealized Gains |
|
27,192
|
| Equity securities, Gross Unrealized Losses |
|
0
|
| Equity securities, Fair Value |
|
96,004
|
| Equity securities, OTTI Recognized in Accumulated OCI |
|
0
|
| Short-term investments |
|
|
| Equity Securities |
|
|
| Equity securities, Amortized cost |
0
|
2,541
|
| Equity securities, Gross Unrealized Gains |
0
|
0
|
| Equity securities, Gross Unrealized Losses |
0
|
0
|
| Equity securities, Fair Value |
0
|
2,541
|
| Equity securities, OTTI Recognized in Accumulated OCI |
$ 0
|
$ 0
|