Note 8 - Financial Highlights (Details) - Net Asset Values and Financial Highlights (iShares S&P Commodity-Indexed Trust [Member], USD $)	9 Months Ended
	Sep. 30, 2013
iShares S&P Commodity-Indexed Trust [Member]
Note 8 - Financial Highlights (Details) - Net Asset Values and Financial Highlights [Line Items]
Net asset value per Share, beginning of period	$ 32.84
Net decrease in net assets from operations	$ (0.46)
Net asset value per Share, end of period	$ 32.38
Net investment loss(a)	(0.69%)	[1]
Expenses(a)	0.75%	[1]
Total return(b)	(1.40%)	[2]
Net investment loss	$ (0.17)
Realized and unrealized loss	$ (0.29)

[1] Percentage is annualized.

[2] Percentage is not annualized.