Restructuring - Restructuring Activities and Related Reserves (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Restructuring Cost And Reserve [Line Items]
Reserve balance	$ 19	$ 10
Charges	21	29	$ 35
Costs charged against assets and other	(5)	(4)
Cash paid	(24)	(15)
Foreign currency translation adjustment	(2)	(1)
Reserve balance	9	19	10
Severance and Employee Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	16	7
Charges	9	18
Cash paid	(18)	(8)
Foreign currency translation adjustment	(2)	(1)
Reserve balance	5	16	7
Environmental Remediation [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	2	2
Charges		1
Cash paid		(1)
Reserve balance	2	2	2
Asset Impairment and Accelerated Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Charges	5	4
Costs charged against assets and other	(5)	(4)
Asset Sales [Member]
Restructuring Cost And Reserve [Line Items]
Charges		1
Cash paid		(1)
Other [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	1	1
Charges	7	5
Cash paid	(6)	(5)
Reserve balance	$ 2	$ 1	$ 1