Statements of Changes in Net Assets (Unaudited) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Net Assets, Beginning of Period	$ 11,544,738,146	$ 10,147,507,137
Operations:
Net investment loss	(7,619,352)	(27,533,111)
Net realized gain (loss), fair value	5,847,432	23,491,426
Net change in unrealized appreciation/depreciation	114,176,495	(194,080,795)
Net increase in net assets resulting from operations	112,404,575	(198,122,480)
Capital Share Transactions:
Contributions for Shares issued	1,064,902,289	3,078,649,161
Distributions for Shares redeemed	(165,713,340)	(1,483,295,672)
Net increase in net assets from capital share transactions	899,188,949	1,595,353,489
Increase in net assets	1,011,593,524	1,397,231,009
Net Assets, End of Period	$ 12,556,331,670	$ 11,544,738,146
Shares issued and redeemed
Shares issued (in shares)	85,500,000	247,000,000
Shares redeemed (in shares)	(13,350,000)	(121,700,000)
Net increase in Shares issued and outstanding (in shares)	72,150,000	125,300,000