Restructuring - Restructuring Activities and Related Reserves (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2015 USD ($)
Restructuring Cost And Reserve [Line Items]
Reserve balance	$ 9
Charges (credit)	48
Costs charged against assets / liabilities	(28)
Cash (paid) received	(7)
Reserve balance	22
Severance and Employee Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	5
Charges (credit)	25
Cash (paid) received	(11)
Reserve balance	19
Environmental Remediation [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	2
Reserve balance	2
Asset Sales [Member]
Restructuring Cost And Reserve [Line Items]
Charges (credit)	(2)
Costs charged against assets / liabilities	(5)
Cash (paid) received	7
Asset Impairment and Accelerated Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Charges (credit)	23
Costs charged against assets / liabilities	(23)
Other [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	2
Charges (credit)	2
Cash (paid) received	(3)
Reserve balance	$ 1