Statements of Changes in Net Assets (Unaudited) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Net Assets, Beginning of Period	$ 10,147,507,137	$ 7,310,131,020
Operations:
Net investment loss	(20,757,047)	(21,630,631)
Net realized gain	27,252,863	22,215,914
Net change in unrealized appreciation/depreciation	(1,023,390,704)	881,278,079
Net increase (decrease) in net assets resulting from operations	(1,016,894,888)	881,863,362
Capital Share Transactions:
Contributions for Shares issued	2,482,260,820	2,782,113,163
Distributions for Shares redeemed	(1,400,676,047)	(826,600,408)
Net increase in net assets from capital share transactions	1,081,584,773	1,955,512,755
Increase in net assets	64,689,885	2,837,376,117
Net Assets, End of Period	$ 10,212,197,022	$ 10,147,507,137
Shares issued and redeemed
Shares issued (in shares)	196,850,000	228,250,000
Shares redeemed (in shares)	(114,500,000)	(68,350,000)
Net increase in Shares issued and outstanding (in shares)	82,350,000	159,900,000