Condensed Statements of Changes in Partners' Capital (USD $)	Total	General Partner [Member]	Limited Partners [Member]
Balances, at at Dec. 31, 2012	$ 1,186,272,656	$ 0	$ 1,186,272,656
Net asset value, beginning of period at Dec. 31, 2012	$ 18.87
Addition of 23,300,000 partnership units	450,453,342	0	450,453,342
Redemption of 43,400,000 partnership units	(863,136,681)	0	(863,136,681)
Net income	164,120,955	0	164,120,955
Balances, at at Mar. 31, 2013	$ 937,710,272	$ 0	$ 937,710,272
Net asset value, beginning of period at Mar. 31, 2013	$ 21.93