| Cover | Aug. 23, 2021 |
| Affiliate, Collateralized Security [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 23, 2021 |
| Entity File Number | 001-34833 |
| Entity Registrant Name | UNITED STATES COMMODITY INDEX FUNDS TRUST |
| Entity Central Index Key | 0001479247 |
| Entity Tax Identification Number | 27-1537655 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1850 Mt. Diablo Boulevard |
| Entity Address, Address Line Two | Suite 640 |
| Entity Address, City or Town | Walnut Creek |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94596 |
| City Area Code | (510) |
| Local Phone Number | 522-9600 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Shares of United States Commodity Index Fund | |
| Affiliate, Collateralized Security [Line Items] | |
| Title of 12(b) Security | Shares of United States Commodity Index Fund |
| Trading Symbol | USCI |
| Security Exchange Name | NYSEArca |
| Shares of United States Copper Index Fund | |
| Affiliate, Collateralized Security [Line Items] | |
| Title of 12(b) Security | Shares of United States Copper Index Fund |
| Trading Symbol | CPER |
| Security Exchange Name | NYSEArca |
