Investments - Other Investments (Details) - USD ($) $ in Thousands |
Sep. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Schedule of Investments [Line Items] | ||
| Other investments | $ 7,041 | $ 13,060 |
| % of Total fair value | 100.00% | 100.00% |
| Investments in limited partnerships [Member] | ||
| Schedule of Investments [Line Items] | ||
| Other investments | $ 5,541 | $ 5,474 |
| % of Total fair value | 78.70% | 41.90% |
| Unfunded commitment on investments in limited partnerships | $ 319 | $ 463 |
| Investment in quoted equity [Member] | ||
| Schedule of Investments [Line Items] | ||
| Other investments | $ 0 | $ 6,586 |
| % of Total fair value | 0.00% | 50.40% |
| Other [Member] | ||
| Schedule of Investments [Line Items] | ||
| Other investments | $ 1,500 | $ 1,000 |
| % of Total fair value | 21.30% | 7.70% |