Statements of Cash Flows (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]
Cash Flows from Operating Activities
Net gain (loss)	$ 42,911,419	$ 133,891,454	$ (23,975,993)	$ 32,179,923
Adjustments to reconcile net gain (loss) to net cash provided by (used in) operating activities:
Increase in investment in iShares® S&P GSCI™ Commodity-Indexed Investing Pool LLC			(106,386,079)	(12,319,155)
Net cash provided by (used in) operating activities			(130,362,072)	19,860,768
Cash Flows from Financing Activities
Contributions			263,677,995	53,845,870
Redemptions			(133,315,923)	(73,706,638)
Net cash provided by (used in) financing activities			130,362,072	(19,860,768)
Net increase in cash and cash equivalents			0	0
Cash and Cash Equivalents
Beginning of period			0	0
End of period	$ 0	$ 0	$ 0	$ 0