Condensed Statement of Changes in Capital (Parenthetical) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	May 08, 2019
United States Commodity Index Fund
Sponsors' shares capital	$ 235,500,454		$ 235,500,454
Sponsor	$ 0		$ 0
United States Commodity Index Fund | Shareholders
Additions	150,000	300,000	3,000,000	650,000
Redemptions	(200,000)	(1,450,000)	(650,000)	(2,200,000)
Shares Outstanding	0	0	0	0
Sponsors' shares capital	$ 235,500,454	$ 107,028,120	$ 235,500,454	$ 107,028,120	$ 234,673,948	$ 126,548,740
United States Copper Index Fund
Sponsors' shares capital	237,771,844		237,771,844
Sponsor	$ 0		$ 0
United States Copper Index Fund | Shareholders
Additions	1,050,000	1,200,000	12,250,000	1,750,000
Redemptions	(3,200,000)	(600,000)	(5,750,000)	(650,000)
Shares Outstanding	0	0	0	0
Sponsors' shares capital	$ 237,771,844	$ 28,151,482	$ 237,771,844	$ 28,151,482	306,368,077	15,293,972
USCF Crescent Crypto Index Fund
Sponsor							$ 1,000
USCF Crescent Crypto Index Fund | Sponsor
Sponsors' shares capital	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Sponsor							$ 1,000
USCF Crescent Crypto Index Fund | Shareholders
Shares Outstanding	0	0	0	0
Sponsors' shares capital	$ 0	$ 0	$ 0	$ 0
United States Commodity Index Funds Trust
Sponsors' shares capital	473,272,298		473,272,298
Sponsor	$ 0		$ 0
United States Commodity Index Funds Trust | Sponsor
Shares Outstanding					0	0
United States Commodity Index Funds Trust | Shareholders
Additions	1,200,000	1,500,000	15,250,000	2,400,000
Redemptions	(3,400,000)	(2,050,000)	(6,400,000)	(2,850,000)
Sponsors' shares capital	$ 473,272,298	$ 135,179,602	$ 473,272,298	$ 135,179,602	$ 541,042,025	$ 141,842,712