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]	$ 6,213,387	[1]	$ 6,271,029
Operations:
Net investment loss		(11,678)		(16,628)	[2]
Net realized gain (loss)		(33,699)		14,369	[2]
Net change in unrealized appreciation/depreciation		(444,581)		(40,158)	[2]
Net decrease in net assets resulting from operations		(489,958)		(42,417)	[2]
Capital Share Transactions:
Contributions for Shares issued		628,701		590,757	[2]
Distributions for Shares redeemed		(599,348)		(605,982)	[2]
Net increase (decrease) in net assets from capital share transactions		29,353		(15,225)	[2]
Decrease in net assets		(460,605)		(57,642)	[2]
Net Assets, End of Period		$ 5,752,782		$ 6,213,387	[1],[2]
Shares issued and redeemed
Shares issued (in Shares)		53,400,000		48,100,000	[2]
Shares redeemed (in Shares)		(54,150,000)		(50,700,000)	[2]
Net decrease in Shares issued and outstanding (in Shares)		(750,000)		(2,600,000)	[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.