v3.8.0.1

Financial Highlights (Net Investment Income Ratio To Average Equity) (Details) | 3 Months Ended | 9 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Investment Company, Financial Highlights [Abstract] |  |  |  |  |
Net Investment Income (Loss) Ratio | [1],[2] | 4.95% | 3.80% | 5.86% | 5.14%
[1] | Average equity is calculated using month end values.
[2] | Includes all items of income and expense on an annualized basis.

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- Definition Percentage of investment income (loss) to average net assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 205 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=25866437&loc=d3e10328-115837 + Details
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