Stockholders' Equity - Share Repurchases in the Open Market (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions			3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2016		Jun. 30, 2016
Stockholders' Equity Note [Abstract]
Shares repurchased in the open market	[1]	2	20	[2]	70	[2]
Average repurchase price per share	[2],[3]		$ 77.74		$ 76.11
Total cost		$ 150	$ 1,536	[2]	$ 5,300	[2]

[1] All shares repurchased in the open market have been retired and constitute authorized but unissued shares.

[2] Shares repurchased in the open market reflect repurchases settled on or before June 30, 2016. The Company repurchased an additional 2 million shares for $150 million at the end of June, which did not settle until July 2016.

[3] Figures in the table may not recalculate exactly due to rounding. Average repurchase price per share is calculated based on unrounded numbers.