FEES PAID BY EACH TRUST SERIES AND RELATED PARTY TRANSACTIONS - (Details) - USD ($)		9 Months Ended		12 Months Ended
	Apr. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021
Fees Paid and Related Party Transactions
Trustee annual fee		$ 3,300
Directors and Officers Liability Insurance | Forecast
Fees Paid and Related Party Transactions
Noninterest Expense Directors Fees				$ 1,061,000
United States Commodity Index Fund
Fees Paid and Related Party Transactions
Registration fees and offering expenses		$ 22,996	$ 0
Number of additional shares of trust registered	10,000,000
United States Commodity Index Fund | Forecast
Fees Paid and Related Party Transactions
Noninterest Expense Directors Fees				48,000
Estimated investor tax reporting cost				215,000
United States Commodity Index Fund | Effective January 1, 2016
Fees Paid and Related Party Transactions
Percentage of average daily net assets paid		0.80%
United States Copper Index Fund
Fees Paid and Related Party Transactions
Registration fees and offering expenses		$ 81,989	$ 0
Costs and expenses annual limit for reimbursement		0.15%
Expense waiver		$ 63,274
Number of additional shares of trust registered	50,000,000
United States Copper Index Fund | Forecast
Fees Paid and Related Party Transactions
Noninterest Expense Directors Fees				55,000
Estimated investor tax reporting cost				$ 250,000
United States Agriculture Index Fund | Effective January 1, 2016
Fees Paid and Related Party Transactions
Percentage of average daily net assets paid		0.65%