Financial Highlights (Net Investment Income Ratio To Average Equity) (Details)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financial Highlights [Abstract]
Net Investment Income	[1],[2]	5.22%	8.59%	8.62%

[1] Average equity is calculated using month end values.

[2] Includes incentive fee in calculation which can vary substantially over periods.