Statements of Operations (Unaudited) (iShares S&P Commodity-Indexed Trust [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
iShares S&P Commodity-Indexed Trust [Member]
Investment Income Allocated from iShares® S&P GSCI™ Commodity-Indexed Investing Pool LLC
Interest	$ 94,496	$ 317,614	$ 497,296	$ 685,021
Total investment income	94,496	317,614	497,296	685,021
Expenses Allocated from iShares® S&P GSCI™ Commodity-Indexed Investing Pool LLC
Management fees	2,234,440	2,440,656	6,392,229	7,431,062
Brokerage commissions and fees	0	0	550	3,630
Total expenses	2,234,440	2,440,656	6,392,779	7,434,692
Net investment loss	(2,139,944)	(2,123,042)	(5,895,483)	(6,749,671)
Realized and Unrealized Gain (Loss) Allocated from iShares® S&P GSCI™ Commodity-Indexed Investing Pool LLC
Net realized gain (loss) on short-term investments	1,086	0	5,912	(1,604)
Net realized loss on futures contracts	(944,965)	(55,078)	(7,724,677)	(9,755,133)
Net change in unrealized appreciation/depreciation on futures contracts	45,995,242	136,069,574	(10,361,745)	48,686,331
Net realized and unrealized gain (loss)	45,051,363	136,014,496	(18,080,510)	38,929,594
Net gain (loss)	$ 42,911,419	$ 133,891,454	$ (23,975,993)	$ 32,179,923
Net gain (loss) per Share (in Dollars per share)	$ 1.19	$ 3.45	$ (0.68)	$ 0.81
Weighted-average Shares outstanding (in Shares)	36,134,239	38,782,065	35,071,062	39,547,993