Financial Highlights (Net Investment Income Ratio To Average Equity) (Details) |
3 Months Ended | 6 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
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| Investment Company, Financial Highlights [Abstract] | ||||||||
| Net Investment Income (Loss) Ratio | [1],[2] | 7.34% | 5.24% | 7.01% | 6.31% | |||
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