Financial Highlights (Expense Ratios To Average Shareholders Equity) (Details)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Financial Highlights [Abstract]
Operating expenses before incentive fee and interest expense	(2.94%)	[1]	(3.00%)	[1]	(3.89%)	[1]
Incentive fee	(4.43%)	[1]	(0.16%)	[1]	(1.37%)	[1]
Interest expense	(1.80%)	[1]	(1.72%)	[1]	(1.18%)	[1]
Total Expenses	(9.17%)	[1]	(4.88%)	[1]	(6.44%)	[1]

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