Statements of Changes in Net Assets (Unaudited) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2015		Dec. 31, 2014
Net Assets, Beginning of Period	[2]	$ 5,260,802	[1]	$ 6,240,747
Operations:
Net investment loss		(19,388)		(31,579)	[2]
Net realized loss		(141,641)		(78,450)	[2]
Net change in unrealized appreciation/depreciation		(274,578)		(1,123,610)	[2]
Net decrease in net assets resulting from operations		(435,607)		(1,233,639)	[2]
Capital Share Transactions:
Contributions for Shares issued		664,967		1,361,917	[2]
Distributions for Shares redeemed		(825,652)		(1,108,223)	[2]
Net increase (decrease) in net assets from capital share transactions		(160,685)		253,694	[2]
Decrease in net assets		(596,292)		(979,945)	[2]
Net Assets, End of Period		$ 4,664,510		$ 5,260,802	[1],[2]
Shares issued and redeemed
Shares issued (in Shares)		43,050,000		74,950,000	[2]
Shares redeemed (in Shares)		(53,300,000)		(63,450,000)	[2]
Net increase (decrease) in Shares issued and outstanding (in Shares)		(10,250,000)		11,500,000	[2]

[1] Previously reported as "Balance Sheets." Please refer to Note 2A.

[2] Previously reported as "Statements of Changes in Shareholders' Equity (Deficit)." Please refer to Note 2A.