Financial Highlights (Net Investment Income Ratio To Average Equity) (Details)		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Financial Highlights [Abstract]
Net Investment Income	[1],[2]	7.36%	6.58%

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

[2] Includes all items of income and expense on an annualized basis.