Financial Highlights (Expense Ratios To Average Shareholders Equity) (Details)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Financial Highlights [Abstract]
Operating expenses before incentive fee and interest expense	(2.93%)	[1],[2]	(3.12%)	[1],[2]	(2.97%)	[1],[2]	(3.10%)	[1],[2]
Incentive fee	(2.14%)	[1],[2]	0.00%	[1],[2]	(2.88%)	[1],[2]	(0.16%)	[1],[2]
Interest expense	(1.74%)	[1],[2]	(1.70%)	[1],[2]	(1.88%)	[1],[2]	(1.64%)	[1],[2]
Total Expenses	(6.81%)	[1],[2]	(4.82%)	[1],[2]	(7.73%)	[1],[2]	(4.90%)	[1],[2]

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

[2] Ratios are annualized except for the incentive fee which is not annualized.