Statements of Changes in Net Assets (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Net Assets, Beginning of Period	$ 6,213,387	[1],[2]	$ 6,271,029	[1]
Operations:
Net investment loss	(3,992)		(16,628)	[1]
Net realized gain (loss)	(303)		14,369	[1]
Net change in unrealized appreciation/depreciation	(77,196)		(40,158)	[1]
Net decrease in net assets resulting from operations	(81,491)		(42,417)	[1]
Capital Share Transactions:
Contributions for Shares issued	412,281		590,757	[1]
Distributions for Shares redeemed	(251,695)		(605,982)	[1]
Net increase (decrease) in net assets from capital share transactions	160,586		(15,225)	[1]
Increase (decrease) in net assets	79,095		(57,642)	[1]
Net Assets, End of Period	$ 6,292,482		$ 6,213,387	[1],[2]
Shares issued and redeemed
Shares issued (in Shares)	34,300,000		48,100,000	[1]
Shares redeemed (in Shares)	(21,550,000)		(50,700,000)	[1]
Net increase (decrease) in Shares issued and outstanding (in Shares)	12,750,000		(2,600,000)	[1]

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

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