Employee Benefit Plans (Change in Benefit Obligations and Change in Plan Assets) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2010
Employee Benefit Plans [Line Items]
Fair value of plan assets at end of year	$ 505		$ 300
U.S. Pension Benefits [Member]
Employee Benefit Plans [Line Items]
Benefit obligation at beginning of year	147		143
Service cost	5		5		5
Interest cost	7		6		7
Loss (gain) from changes in actuarial assumptions	12		2
Benefits paid	(11)	[1]	(9)	[1]
Settlements or curtailment gain	(1)
Acquisition of Norit	36
Benefit obligation at end of year	195		147		143
Fair value of plan assets at beginning of year	103		104
Actual return on plan assets	23		8
Employer contribution	8
Benefits paid	(11)	[1]	(9)	[1]
Acquisition of Norit	27
Expenses paid from assets	(1)
Fair value of plan assets at end of year	149		103		104
Funded status	(46)		(44)
Recognized liability	(46)	[2]	(44)	[2]
Foreign Pension Benefits [Member]
Employee Benefit Plans [Line Items]
Benefit obligation at beginning of year	236		241
Service cost	7		6		5
Interest cost	11		11		11
Plan participants' contribution	1		1
Foreign currency exchange rate changes	5		1
Loss (gain) from changes in actuarial assumptions	38		(9)
Benefits paid	(11)	[1]	(16)	[1]
Settlements or curtailment gain	(4)		(1)
Acquisition of Norit	140
Other	(1)		2
Benefit obligation at end of year	422		236		241
Fair value of plan assets at beginning of year	197		197
Actual return on plan assets	24		2
Employer contribution	13		13
Plan participants' contribution	1		1
Foreign currency exchange rate changes	5
Benefits paid	(11)	[1]	(16)	[1]
Settlements	(5)
Acquisition of Norit	133
Expenses paid from assets	(1)
Fair value of plan assets at end of year	356		197		197
Funded status	(66)		(39)
Recognized liability	(66)	[2]	(39)	[2]
U. S. Postretirement Benefits [Member]
Employee Benefit Plans [Line Items]
Benefit obligation at beginning of year	64		69
Service cost	1		1		1
Interest cost	2		2		3
Loss (gain) from changes in actuarial assumptions	1		(1)
Benefits paid	(5)	[1]	(5)	[1]
Plan amendments			(2)
Settlements or curtailment gain	(1)
Acquisition of Norit	2
Benefit obligation at end of year	64		64		69
Employer contribution	5		5
Benefits paid	(5)	[1]	(5)	[1]
Funded status	(64)		(64)
Recognized liability	(64)	[2]	(64)	[2]
Foreign Postretirement Benefits [Member]
Employee Benefit Plans [Line Items]
Benefit obligation at beginning of year	15		15
Interest cost	1		1		1
Foreign currency exchange rate changes	1
Loss (gain) from changes in actuarial assumptions	2		(1)
Benefits paid	(1)	[1]
Benefit obligation at end of year	18		15		15
Employer contribution	1
Benefits paid	(1)	[1]
Funded status	(18)		(15)
Recognized liability	$ (18)	[2]	$ (15)	[2]

[1] Included in this amount is $7 million and $2 million that the Company paid directly to the participants in its defined benefit plans in fiscal 2012 and 2011, respectively.

[2] Included in this amount is $4 million of net pension liability as of September 30, 2011 related to the Supermetals Business presented as Noncurrent liabilities held for sale in the Consolidated Balance Sheet.