Schedules of Investments (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Investment [Table Text Block]

Security Description	Face Amount		Fair Value
U.S. Treasury bills(a)(b):
1.56% due 01/07/20	$	50,000,000	$	49,990,521
1.54% - 1.87% due 01/16/20		85,000,000		84,953,805
1.62% due 01/21/20		50,600,000		50,560,743
1.87% due 01/23/20		50,000,000		49,957,125
1.55% due 01/30/20		100,000,000		99,886,820
1.56% due 02/04/20		15,000,000		14,978,480
1.88% - 1.93% due 02/06/20		70,000,000		69,898,597
1.55% due 02/13/20		65,000,000		64,887,198
1.55% due 02/20/20		30,000,000		29,938,138
1.81% due 02/27/20		15,000,000		14,964,767
1.53% - 1.61% due 03/12/20		75,000,000		74,780,885
1.55% due 03/26/20		25,000,000		24,912,048
1.55% due 04/16/20		35,000,000		34,845,071
1.55% - 1.61% due 04/23/20		55,000,000		54,737,729
1.51% due 05/07/20		15,000,000		14,920,003
1.55% due 05/14/20		16,400,000		16,307,435
Total U.S. Treasury bills (Cost: $750,419,242)				750,519,365
Total Investments – 96.80%				750,519,365
Other Assets, Less Liabilities – 3.20%				24,823,740
Net Assets – 100.00%			$	775,343,105

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

Schedule of Derivative Instruments [Table Text Block]

Number of Contracts	Expiration Date	Current Notional Amount		Net Unrealized Appreciation (Depreciation)
32,510	March 16, 2020	$	773,217,840	$	19,634,651

Number of Contracts	Expiration Date	Current Notional Amount		Net Unrealized Appreciation (Depreciation)
57,905	March 15, 2019	$	1,200,110,078	$	(116,523,249	)