Financial Highlights (Net Investment Income Ratio To Average Shareholders Equity) (Details)	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Financial Highlights [Abstract]
Net Investment Income	10.72%	[1],[2]	12.43%	[1],[2]	10.84%	[1],[2]	11.73%	[1],[2]

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

[2] Includes all items of income and expenses on an annualized basis except for incentive fee expense which is included on a non-annualized basis.