Financial Highlights (Expense Ratios To Average Equity) (Details)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Financial Highlights [Abstract]
Operating expenses before incentive fee, interest expense, and other investment related expenses	(2.67%)	[1]	(2.93%)	[1]	(2.77%)	[1]	(2.97%)	[1]
Ratio Of Incentive Fee To Average Equity	(0.32%)	[1]	(2.14%)	[1]	(0.91%)	[1]	(2.88%)	[1]
Interest expense and other investment related expenses	(2.11%)	[1]	(1.74%)	[1]	(1.94%)	[1]	(1.88%)	[1]
Total Expenses	(5.10%)	[1]	(6.81%)	[1]	(5.62%)	[1]	(7.73%)	[1]

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