Note 10 - Investment Valuation (Details) - Valuation of the Investing Pool’s Investments by the Fair Value Hierarchy (iShares S&P Commodity-Indexed Investing Pool LLC [Member], USD $)	Sep. 30, 2013		Dec. 31, 2012
Futures [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, fair value	$ (74,864,742)	[1]	$ (64,502,960)	[1]
Futures [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, fair value	(74,864,742)	[1]	(64,502,960)	[1]
US Treasury Bill Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, fair value	1,251,930,274		1,111,734,878
US Treasury Bill Securities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, fair value	$ 1,251,930,274		$ 1,111,734,878

[1] Futures contracts are valued at unrealized appreciation (depreciation).