v2.4.0.6
Financial Highlights (Net Asset Based Total Return For A Shareholder) (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Financial Highlights [Abstract]        
Total Return before Incentive Fee 6.24% [1] (0.31%) [1] 19.06% [1] 2.11% [1]
Incentive Fee (1.99%) [1] 0.00% [1] (2.75%) [1] (0.17%) [1]
Total Return after Incentive Fee 4.25% [1] (0.31%) [1] 16.31% [1] 1.94% [1]
[1] Total return is calculated for all shareholders' equity accounts, excluding the Managers' shareholder equity, taken as a whole for each period. Total return is calculated assuming reinvestment of all distributions at shareholders' equity per share during the period.