Investments - Other Investments (Details) - USD ($) $ in Thousands |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Schedule of Investments [Line Items] | ||
| Fair value | $ 28,431 | $ 23,716 |
| % of Total fair value | 100.00% | 100.00% |
| Investment in limited partnerships | ||
| Schedule of Investments [Line Items] | ||
| Fair value | $ 3,258 | $ 3,833 |
| % of Total fair value | 11.50% | 16.20% |
| Unfunded commitment on investments in limited partnerships | $ 340 | $ 414 |
| Investment in special purpose vehicles focused on lending activities | ||
| Schedule of Investments [Line Items] | ||
| Fair value | $ 23,373 | $ 18,383 |
| % of Total fair value | 82.20% | 77.50% |
| Unfunded commitment on investments in limited partnerships | $ 3,516 | $ 7,359 |
| Other investments | ||
| Schedule of Investments [Line Items] | ||
| Fair value | $ 1,800 | $ 1,500 |
| % of Total fair value | 6.30% | 6.30% |