Condensed Statements of Operations (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Gain (loss) on trading of commodity contracts:
Realized gain (loss) on closed futures contracts	$ 88,254,202	$ (299,391,078)
Realized gain (loss) on closed swap contracts	22,564,790	(91,376,797)
Change in unrealized gain (loss) on open futures contracts	48,310,023	(33,696,980)
Change in unrealized gain (loss) on open swap contracts	7,555,254	(3,365,324)
Dividend income	36,688	24,301
Interest income	57,108	30,138
Other income	60,000	42,000
Total income (loss)	166,838,065	(427,733,740)
Expenses
General Partner management fees (Note 3)	1,561,162	1,379,693
Brokerage commissions	669,710	1,021,391
Professional fees	401,872	296,641
Other expenses	84,366	61,042
Total expenses	2,717,110	2,758,767
Net income (loss)	$ 164,120,955	$ (430,492,507)
Net income (loss) per limited partnership unit	3.06	(9.87)
Net income (loss) per weighted average limited partnership unit	2.97	(9.76)
Weighted average limited partnership units outstanding	55,219,809	44,091,606