FINANCIAL HIGHLIGHTS - Per Unit Performance Data and Other Supplemental Financial Data (Details) - $ / shares		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
United States Commodity Index Fund
Per Share Operating Performance:
Net asset value, beginning of period (in dollars per share)		$ 40.46	$ 26.64	$ 32.58	$ 36.87
Total income (loss)		0.60	3.17	8.67	(6.90)
Total expenses		(0.10)	(0.08)	(0.29)	(0.24)
Net increase (decrease) in net asset value		0.50	3.09	8.38	(7.14)
Net asset value, end of period (in dollars per share)		$ 40.96	$ 29.73	$ 40.96	$ 29.73
Total Return		1.24%	11.60%	25.72%	(19.37%)
Ratios to Average Net Assets
Total income (loss)		1.45%	12.54%	20.93%	(25.06%)
Management fees	[1]	0.80%	0.80%	0.80%	0.80%
Total expenses excluding management fees	[1]	0.19%	0.30%	0.22%	0.31%
Net expense excluding management fees	[1]	0.19%	0.30%	0.22%	0.31%
Net income (loss)		1.21%	12.26%	20.16%	(25.89%)
United States Copper Index Fund
Per Share Operating Performance:
Net asset value, beginning of period (in dollars per share)		$ 26.30	$ 16.99	$ 21.72	$ 17.54
Total income (loss)		(1.21)	1.82	3.48	1.33
Total expenses		(0.06)	(0.04)	(0.17)	(0.10)
Net increase (decrease) in net asset value		(1.27)	1.78	3.31	1.23
Net asset value, end of period (in dollars per share)		$ 25.03	$ 18.77	$ 25.03	$ 18.77
Total Return		(4.83%)	10.48%	15.24%	7.01%
Ratios to Average Net Assets
Total income (loss)		(4.85%)	9.26%	1.49%	18.61%
Management fees	[1]	0.65%	0.65%	0.65%	0.65%
Total expenses excluding management fees	[1]	0.22%	0.40%	0.24%	0.51%
Expense waived	[1],[2]		(0.25%)	(0.04%)	(0.36%)
Net expense excluding management fees	[1],[2]	0.22%	0.15%	0.20%	0.15%
Net income (loss)		(5.07%)	9.06%	0.86%	18.01%

[1] Annualized.

[2] USCF paid certain expenses on a discretionary basis typically borne by CPER where expenses exceeded 0.15% (15 basis points) of CPER’s NAV, on an annualized basis. USCF terminated the expense waiver as of April 30, 2021.