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FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS - (Details) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2021	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2026
FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS
Trustee annual fee				$ 3,300
Directors and Officers Liability Insurance \| Subsequent event \| Forecast
FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS
Fees and expenses						$ 881,000
United States Commodity Index Fund
FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS
Percentage of average daily net assets paid		0.80%		0.80%
Registration fees and offering expenses				$ 0	$ 0
Number of additional shares which were registered	10,000,000
Fees and expenses		$ 21,609	$ 9,258	$ 47,957	22,028
United States Commodity Index Fund \| Subsequent event \| Forecast
FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS
Fees and expenses						77,000
Estimated investor tax reporting costs and audit expenses						370,000
United States Copper Index Fund
FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS
Percentage of average daily net assets paid		0.65%		0.65%
Registration fees and offering expenses				$ 0	0
Number of additional shares which were registered	50,000,000
Fees and expenses		$ 38,598	$ 7,073	$ 74,902	$ 16,849
United States Copper Index Fund \| Subsequent event \| Forecast
FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS
Fees and expenses						150,000
Estimated investor tax reporting costs and audit expenses						$ 600,000