Investments - Net Investment Income (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Schedule of Investments [Line Items] | ||||
| Investment income | $ 42,750 | $ 37,446 | $ 129,078 | $ 112,413 |
| Investment expenses | (1,927) | (1,780) | (5,586) | (5,122) |
| Net investment income | 40,823 | 35,666 | 123,492 | 107,291 |
| Fixed maturities [Member] | ||||
| Schedule of Investments [Line Items] | ||||
| Investment income | 40,369 | 35,769 | 123,849 | 108,018 |
| Cash and cash equivalents [Member] | ||||
| Schedule of Investments [Line Items] | ||||
| Investment income | 899 | 506 | 1,328 | 1,147 |
| Loans to related party [Member] | ||||
| Schedule of Investments [Line Items] | ||||
| Investment income | 913 | 599 | 2,441 | 1,729 |
| Other [Member] | ||||
| Schedule of Investments [Line Items] | ||||
| Investment income | $ 569 | $ 572 | $ 1,460 | $ 1,519 |