QUARTERLY FINANCIAL DATA (Unaudited) (Summary of Quarterly Financial Information) (Details) - USD ($)	3 Months Ended	12 Months Ended
Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data [Line Items]
Total Income (Loss)									$ (4,241,306)	$ (68,867,799)	$ 34,053,171
Total Expenses									3,969,737	6,145,146	5,533,116
Expense waivers									(67,628)	(77,884)	(85,686)
Net expenses									3,902,109	6,067,262	5,447,430
Net income (loss)									(8,143,415)	(74,935,061)	28,605,741
United States Commodity Index Fund
Quarterly Financial Data [Line Items]
Total Income (Loss)	$ 6,543,450	$ (10,523,581)	$ (18,135,475)	$ 17,519,370	$ (65,771,228)	$ (19,156,279)	$ 14,855,407	$ 4,264,134	(4,596,236)	(65,807,966)	31,840,731
Total Expenses	605,786	833,737	1,102,290	1,275,883	1,396,043	1,639,497	1,536,430	1,391,035	3,817,696	5,963,005	5,349,811
Net income (loss)	$ 5,937,664	$ (11,357,318)	$ (19,237,765)	$ 16,243,487	$ (67,167,271)	$ (20,795,776)	$ 13,318,977	$ 2,873,099	$ (8,413,932)	$ (71,770,971)	$ 26,490,920
Net Income (Loss) per Share	$ 1.03	$ (1.14)	$ (1.83)	$ 1.32	$ (4.97)	$ (1.24)	$ 0.98	$ 0.24	$ (0.62)	$ (4.99)	$ 2.46
United States Copper Index Fund
Quarterly Financial Data [Line Items]
Total Income (Loss)	$ 697,689	$ (473,662)	$ (1,111,271)	$ 1,242,174	$ (747,096)	$ (582,529)	$ (389,444)	$ (1,178,835)	$ 354,930	$ (2,897,904)	$ 2,347,392
Total Expenses	27,169	30,913	49,021	44,938	39,211	37,461	33,533	35,759	152,041	145,964	122,952
Expense waivers	(11,210)	(12,147)	(22,353)	(21,918)	(16,628)	(15,472)	(10,931)	(8,269)	(67,628)	(51,300)	(40,153)
Net expenses	15,959	18,766	26,668	23,020	22,583	21,989	22,602	27,490	84,413	94,664	82,799
Net income (loss)	$ 681,730	$ (492,428)	$ (1,137,939)	$ 1,219,154	$ (769,679)	$ (604,518)	$ (412,046)	$ (1,206,325)	$ 270,517	$ (2,992,568)	$ 2,264,593
Net Income (Loss) per Share	$ 1.38	$ (0.83)	$ (1.37)	$ 1.92	$ (1.16)	$ (1.12)	$ (0.58)	$ (1.75)	$ 1.10	$ (4.61)	$ 4.69

Total Income (Loss)

$ (4,241,306)

$ (68,867,799)

$ 34,053,171

Expense waivers

(67,628)

(77,884)

(85,686)

Quarterly Financial Data [Line Items]

Total Expenses

605,786

833,737

1,102,290

1,275,883

1,396,043

1,639,497

1,536,430

1,391,035

3,817,696

5,963,005

5,349,811

Net Income (Loss) per Share

$ 1.03

$ (1.14)

$ (1.83)

$ 1.32

$ (4.97)

$ (1.24)

$ 0.98

$ 0.24

$ (0.62)

$ (4.99)

$ 2.46

Quarterly Financial Data [Line Items]

Total Expenses

27,169

30,913

49,021

44,938

39,211

37,461

33,533

35,759

152,041

145,964

122,952

Net Income (Loss) per Share

$ 1.38

$ (0.83)

$ (1.37)

$ 1.92

$ (1.16)

$ (1.12)

$ (0.58)

$ (1.75)

$ 1.10

$ (4.61)

$ 4.69