Stockholders' Equity - Schedule of Activity in Noncontrolling Interests (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Equity [Abstract]
Balance at September 30			$ 122	$ 132
Net income attributable to noncontrolling interests	$ 2	$ 5	7	14
Noncontrolling interest foreign currency translation adjustment			(3)	(2)
Noncontrolling interest dividends			(22)	(25)
Balance at June 30	$ 104	$ 119	$ 104	$ 119