Statements of Financial Condition - USD ($)		Dec. 31, 2017	Dec. 31, 2016
Assets
United States Treasury Obligations, at value (cost $514,764,046 and $702,232,971, respectively)		$ 514,714,860	$ 702,215,941
Affiliated Investments, at value (cost $124,826,575 and $19,456,137, respectively)		124,748,306	19,456,137
Other investments:
Variation margin receivable- Commodity Futures Contracts		442,552
Cash held by custodian	[1]	2,260,923	2,181,236
Receivable for:
Dividends from affiliates		33,612	10,304
Total assets		642,200,253	723,863,618
Other investments:
Variation margin payable- Commodity Futures Contracts			114,786
Payable for:
Management fees		444,415	516,160
Brokerage commissions and fees		4,091	3,102
Total liabilities		448,506	634,048
Commitments and Contingencies (Note 10)
Equity
Shareholder's equity—General Shares		750	799
Shareholders' equity—Shares		641,750,997	723,228,771
Total shareholders' equity		641,751,747	723,229,570
Total liabilities and equity		$ 642,200,253	$ 723,863,618
General Shares outstanding		40	40
Shares outstanding		34,200,000	36,200,000
Net asset value per share		$ 18.76	$ 19.98
Market value per share		$ 18.75	$ 19.98

[1] Cash at December 31, 2017, 2016 and 2015 reflects cash held by the Custodian