Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Sep. 30, 2011
Current assets:
Cash and cash equivalents	$ 366	$ 286
Accounts and notes receivable, net of reserve for doubtful accounts of $4 and $4	759	659
Inventories:
Raw materials	119	120
Work in process	4	3
Finished goods	260	233
Other	40	37
Total inventories	423	393
Prepaid expenses and other current assets	73	76
Deferred income taxes	27	35
Current assets held for sale		106
Total current assets	1,648	1,555
Property, plant and equipment, net	1,079	1,036
Goodwill	40	40
Equity affiliates	62	60
Assets held for rent	51	46
Notes receivable from sale of business	263
Deferred income taxes	185	261
Other assets	101	104
Noncurrent assets held for sale		39
Total assets	3,429	3,141
Current liabilities:
Notes payable to banks	79	86
Accounts payable and accrued liabilities	496	461
Income taxes payable	55	34
Deferred income taxes	6	6
Current portion of long-term debt	48	57
Current liabilities held for sale		12
Total current liabilities	684	656
Long-term debt	560	556
Deferred income taxes	9	8
Other liabilities	298	299
Noncurrent liabilities held for sale		6
Commitments and contingencies (Note F)
Preferred stock:
Authorized: 2,000,000 shares of $1 par value Issued and Outstanding: None and none
Common stock:
Authorized: 200,000,000 shares of $1 par value Issued: 63,653,983 and 63,894,443 shares Outstanding 63,399,863 and 63,860,777 shares	64	64
Less cost of 254,120 and 33,666 shares of common treasury stock	(8)	(1)
Additional paid-in capital	17	18
Retained earnings	1,576	1,314
Deferred employee benefits	(11)	(14)
Accumulated other comprehensive income	108	106
Total Cabot Corporation stockholders' equity	1,746	1,487
Noncontrolling interests	132	129
Total stockholders' equity	1,878	1,616
Total liabilities and stockholders' equity	$ 3,429	$ 3,141