Financial Highlights - Financial Highlights (Details) - USD ($) $ / shares in Units, $ in Thousands |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Investment Company, Financial Highlights [Roll Forward] | ||||||||||
| Net asset value at beginning of period (in dollars per share) | $ 8.85 | $ 9.40 | $ 10.39 | $ 11.51 | $ 11.00 | $ 12.20 | $ 12.66 | $ 13.77 | $ 14.52 | $ 14.19 |
| Net investment income (in dollars per share) | 0.53 | 1.13 | 1.07 | 1.02 | 1.03 | 1.45 | 1.42 | 1.57 | 1.40 | 1.55 |
| Net gain (loss) (in dollars per share) | (0.77) | (0.68) | (1.05) | (1.15) | 0.48 | (1.37) | (0.48) | (1.28) | (0.75) | 0.13 |
| Net increase (decrease) in net assets resulting from operations (in dollars per share) | (0.24) | 0.45 | 0.02 | (0.13) | 1.51 | 0.08 | 0.94 | 0.29 | 0.65 | 1.68 |
| Stockholder distributions - income (in dollars per share) | (0.93) | (1.00) | (1.00) | (1.00) | (1.00) | (1.10) | (1.40) | (1.40) | (1.37) | (1.40) |
| Stockholder distributions - capital gains (in dollars per share) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | (0.03) | 0 |
| Stockholder distributions - return of capital (in dollars per share) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Effect of share issuance above (below) NAV (in dollars per share) | 0 | 0 | 0 | 0 | 0 | (0.18) | 0 | 0 | 0 | 0.05 |
| Effect of share repurchases (in dollars per share) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Other (in dollars per share) | 0 | 0 | (0.01) | 0.01 | 0 | |||||
| Net asset value at end of period (in dollars per share) | $ 7.68 | $ 8.85 | $ 9.40 | $ 10.39 | $ 11.51 | $ 11.00 | $ 12.20 | $ 12.66 | $ 13.77 | $ 14.52 |
| Net assets at end of year | $ 166,490 | $ 191,762 | $ 203,724 | $ 225,019 | $ 249,471 | $ 234,434 | $ 249,357 | $ 258,767 | $ 278,699 | $ 240,850 |
| Shares outstanding at end of period (in shares) | 21,666,340 | 21,666,340 | 21,666,340 | 21,666,340 | 21,666,340 | 21,303,540,000 | 20,444,564 | 20,444,564 | 20,239,957 | 16,581,869 |
| Per share market value at end of period (in dollars per share) | $ 6.37 | $ 8.50 | $ 7.07 | $ 8.54 | $ 11.22 | $ 8.03 | $ 10.86 | $ 9.60 | $ 13.75 | $ 15.38 |
| Total return based on market value | (14.58%) | 36.09% | (6.85%) | (15.20%) | 53.26% | (13.86%) | 27.68% | (21.74%) | (1.82%) | 28.95% |
| Total return based on average net asset value | (1.03%) | 6.57% | 1.80% | 0.58% | 14.77% | 5.04% | 8.76% | 3.06% | 4.15% | 12.30% |
| Ratio/Supplemental data: | ||||||||||
| Ratio of net investment income to average net assets | 6.35% | 12.33% | 10.84% | 9.42% | 9.15% | 13.32% | 11.38% | 11.85% | 9.80% | 10.81% |
| Ratio of total expenses to average net assets | 14.73% | 18.08% | 19.14% | 14.60% | 13.07% | 13.68% | 15.35% | 9.84% | 9.46% | 10.81% |
| Portfolio turnover | 10.82% | 18.29% | 12.12% | 24.93% | 41.80% | 25.24% | 27.18% | 31.53% | 39.39% | 22.41% |