Schedules of Investments (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Investment [Table Text Block]

Security Description	Face Amount		Fair Value
U.S. Treasury bills (a)(b) :
2.08% – 2.25% due 01/03/19	$	16,000,000	$	15,999,000
2.32% due 01/08/19		200,000,000		199,925,084
2.30% due 01/10/19		145,000,000		144,927,380
2.29% due 01/15/19		200,000,000		199,835,784
2.30% – 2.33% due 01/22/19		350,000,000		349,552,777
2.28% due 01/24/19		180,000,000		179,748,925
2.40% due 01/29/19		50,000,000		49,909,343
2.41% due 02/14/19		60,000,000		59,828,359
Total U.S. Treasury bills (Cost: $1,199,665,444)				1,199,726,652
Total Investments – 99.16%				1,199,726,652
Other Assets, Less Liabilities – 0.84%				10,139,957
Net Assets – 100.00%			$	1,209,866,609

Security Description	Face Amount		Fair Value
U.S. Treasury bills (a)(b) :
1.17% – 1.20% due 01/04/18	$	116,000,000	$	115,992,693
1.11% – 1.21% due 01/18/18		144,000,000		143,920,719
1.20% due 01/25/18		142,000,000		141,888,412
1.15% due 02/01/18		434,500,000		434,041,811
1.31% due 03/08/18		509,000,000		507,811,007
Total U.S. Treasury bills (Cost: $1,343,671,164)				1,343,654,642
Total Investments – 96.43%				1,343,654,642
Other Assets, Less Liabilities – 3.57%				49,754,123
Net Assets – 100.00%			$	1,393,408,765

Schedule of Derivative Instruments [Table Text Block]

Number of Contracts	Expiration Date	Current Notional Amount		Net Unrealized Appreciation (Depreciation)
57,905	March 2019	$	1,200,110,078	$	(116,523,249	)

Number of Contracts	Expiration Date	Current Notional Amount		Net Unrealized Appreciation (Depreciation)
56,905	March 2018	$	1,388,834,811	$	74,398,485