Financial Highlights (Net Asset Based Total Return For A Shareholder) (Details)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Financial Highlights [Abstract]
Total Return	22.16%	[1],[2]	2.43%	[2]	7.79%	[1],[2]
Total Return excluding accretive effect of share repurchase	22.05%		2.34%

[1] Total return includes the accretive effect of the share repurchase. Had this not been included, total return after incentive fee for the years ended December 31, 2012 and 2011 would have been 22.05% and 2.34%, respectively.

[2] Total return is calculated for all shareholders’ equity accounts taken as a whole for each period. Total return is calculated assuming reinvestment of all distributions at shareholders’ equity per share during the period.