Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 11, 2020	Jun. 30, 2019
Document Information
Document Annual Report	true
Document Transition Report	false
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Entity File Number	001-34833
Entity Registrant Name	United States Commodity Index Funds Trust
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-1537655
Entity Address, Address Line One	1850 Mt. Diablo Boulevard, 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
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 360,389,637
Entity Central Index Key	0001479247
Amendment Flag	false
Common Stock
Document Information
Entity Common Stock, Shares Outstanding		5,500,000
United States Commodity Index Fund
Document Information
Title of 12(b) Security	Shares of United States Commodity Index Fund
Trading Symbol	USCI
Security Exchange Name	NYSEArca
Entity Common Stock, Shares Outstanding		4,900,000
Entity Public Float			349,366,315
United States Copper Index Fund
Document Information
Title of 12(b) Security	Shares of United States Copper Index Fund
Trading Symbol	CPER
Security Exchange Name	NYSEArca
Entity Common Stock, Shares Outstanding		600,000
Entity Public Float			$ 11,023,322