Financial Highlights (Net Investment Income Ratio to Average Equity) (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018
Investment Company, Financial Highlights [Abstract]
Net Investment Income (Loss) Ratio	7.75%	7.20%

Percentage of investment income (loss) to average net assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

Name:	us-gaap_InvestmentCompanyInvestmentIncomeLossRatio
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration