Significant Accounting Policies - Segment Reporting Revenue Percentage (Detail)	12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2011
Reinforcement Materials [Member]
Segment Reporting Information [Line Items]
Revenue, by segment	56.00%		63.00%		65.00%
Performance Materials [Member]
Segment Reporting Information [Line Items]
Revenue, by segment	27.00%		28.00%		29.00%
Advanced Technologies [Member]
Segment Reporting Information [Line Items]
Revenue, by segment	7.00%		7.00%		6.00%
Purification Solutions [Member]
Segment Reporting Information [Line Items]
Revenue, by segment	10.00%	[1]	2.00%	[1]

[1] Fiscal 2012 includes two months of revenue for Purification Solutions, which the Company acquired on July 31, 2012.