XML 29 R30.htm IDEA: XBRL DOCUMENT v2.4.0.6
Summarized (Unaudited) Quarterly Financial Information (Detail) (USD $)
 3 Months Ended 12 Months Ended
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Quarterly Financial Information [Line Items]                      
Total Income (Loss) $ (1,848,278) $ 8,792,836 $ (25,764,862) $ 9,471,904 $ 38,190,454 $ (40,601,303) $ (24,020,290) $ 30,855,365 $ (9,348,400) $ 4,424,226 $ 12,303,709
Total Expenses 220,660 248,705 265,297 315,716 318,177 358,512 498,550 462,485 1,050,378 1,637,724 1,299,784
Net Income (Loss) $ (2,068,938) $ 8,544,131 $ (26,030,159) $ 9,156,188 $ 37,872,277 $ (40,659,815) $ (24,518,840) $ 30,392,880 $ (10,398,778) $ 2,786,502 $ 11,003,925
Net Income (Loss) per Unit (0.59) 2.50 (7.91) 2.35 8.12 (8.45) (4.71) 5.59 (3.65) 0.55 2.54