Investments Investments - Net Investment Income (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Investment Income, Net [Abstract] | ||||
| Investment income | $ 3,727 | $ 2,012 | $ 10,672 | $ 5,537 |
| Investment expenses | (183) | (128) | (555) | (369) |
| Net investment income | $ 3,544 | $ 1,884 | $ 10,117 | $ 5,168 |