Investments - Scheduled Maturities (Details) - USD ($) $ in Thousands |
Jun. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Amortized Cost | ||
| Due in one year or less | $ 124,108 | $ 94,382 |
| Due after one through five years | 134,052 | 173,296 |
| Due after five through ten years | 297,453 | 242,005 |
| Due after ten years | 10,508 | 6,549 |
| Asset-backed securities | 103,242 | 114,456 |
| Amortized Cost | 669,363 | 630,688 |
| Fair Value | ||
| Due in one year or less | 124,153 | 94,584 |
| Due after one through five years | 135,215 | 173,251 |
| Due after five through ten years | 299,591 | 240,060 |
| Due after ten years | 10,488 | 6,413 |
| Asset-backed securities | 104,248 | 114,661 |
| Fair Value | $ 673,695 | $ 628,969 |