Restructuring (Restructuring Activities and Related Reserves) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Restructuring Cost and Reserve [Line Items]
Reserve balance	$ 7		$ 5
Charges	19	9	25	12
Costs charged against assets/liabilities	(17)		(19)
Cash paid	(2)		(4)
Reserve balance	7		7
Severance and Employee Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance	3		2
Charges	2		5
Costs charged against assets/liabilities
Cash paid	(1)		(3)
Reserve balance	4		4
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance	2		1
Charges
Costs charged against assets/liabilities			1
Cash paid
Reserve balance	2		2
Asset Impairment And Accelerated Depreciation [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance
Charges	17		18
Costs charged against assets/liabilities	(17)		(18)
Cash paid
Reserve balance
Other [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance	2		2
Charges			2
Costs charged against assets/liabilities			(2)
Cash paid	(1)		(1)
Reserve balance	$ 1		$ 1