Statements of Changes in Net Assets (Unaudited) - USD ($) $ in Thousands		6 Months Ended		12 Months Ended
		Jun. 30, 2015		Dec. 31, 2014
Net Assets, Beginning of Period	[2]	$ 6,213,387	[1]	$ 6,271,029
Operations:
Net investment loss		(7,964)		(16,628)	[2]
Net realized gain (loss)		(363)		14,369	[2]
Net change in unrealized appreciation/depreciation		(164,265)		(40,158)	[2]
Net decrease in net assets resulting from operations		(172,592)		(42,417)	[2]
Capital Share Transactions:
Contributions for Shares issued		526,719		590,757	[2]
Distributions for Shares redeemed		(251,695)		(605,982)	[2]
Net increase (decrease) in net assets from capital share transactions		275,024		(15,225)	[2]
Increase (decrease) in net assets		102,432		(57,642)	[2]
Net Assets, End of Period		$ 6,315,819		$ 6,213,387	[1],[2]
Shares issued and redeemed
Shares issued (in Shares)		44,200,000		48,100,000	[2]
Shares redeemed (in Shares)		(21,550,000)		(50,700,000)	[2]
Net increase (decrease) in Shares issued and outstanding (in Shares)		22,650,000		(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.