Investments - Scheduled Maturities (Details) - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Amortized Cost | ||
| Due in one year or less | $ 100,443 | $ 62,745 |
| Due after one through five years | 158,761 | 187,633 |
| Due after five through ten years | 238,559 | 193,379 |
| Due after ten years | 10,017 | 19,242 |
| Asset-backed securities | 120,429 | 101,320 |
| Amortized Cost | 628,209 | 564,319 |
| Fair Value | ||
| Due in one year or less | 100,556 | 62,743 |
| Due after one through five years | 161,063 | 186,629 |
| Due after five through ten years | 248,040 | 190,055 |
| Due after ten years | 9,844 | 19,015 |
| Asset-backed securities | 122,069 | 100,793 |
| Fair Value | $ 641,572 | $ 559,235 |