Significant Accounting Policies (Policy)

3 Months Ended

Dec. 31, 2011

Significant Accounting Policies [Abstract]

Revenue Recognition And Accounts Receivable

Revenue Recognition and Accounts Receivable

Cabot recognizes revenue when persuasive evidence of a sales arrangement exists, delivery has occurred, the sales price is fixed or determinable and collectability is probable. Cabot generally is able to ensure that products meet customer specifications prior to shipment. If the Company is unable to determine that the product has met the specified objective criteria prior to shipment or if title has not transferred because of sales terms, the revenue is considered "unearned" and is deferred until the revenue recognition criteria are met.

Shipping and handling charges related to sales transactions are recorded as sales revenue when billed to customers or included in the sales price. Shipping and handling costs are included in cost of sales.

The following table shows the relative size of the revenue recognized in each of the Company's reportable segments:

	Three Months  Ended December 31
	2011			2010
Core Segment		67	%		65	%
Performance Segment		28	%		28	%
New Business Segment		3	%		4	%
Specialty Fluids Segment		2	%		3	%

Cabot derives the substantial majority of its revenues from the sale of products in the Core and Performance Segments. Revenue from these products is typically recognized when the product is shipped and title and risk of loss have passed to the customer. The Company offers certain of its customers cash discounts and volume rebates as sales incentives. The discounts and volume rebates are recorded as a reduction in sales at the time revenue is recognized and are estimated based on historical experience and contractual obligations. Cabot periodically reviews the assumptions underlying its estimates of discounts and volume rebates and adjusts its revenues accordingly.

Revenue in the New Business Segment is typically recognized when the product is shipped and title and risk of loss have passed to the customer. Depending on the nature of the contract with the customer, a portion of the segment's revenue may be recognized using proportional performance.

The majority of the revenue in the Specialty Fluids Segment arises from the rental of cesium formate. This revenue is recognized throughout the rental period based on the contracted rental terms. Customers are also billed and revenue is recognized, typically at the end of the job, for cesium formate product that is not returned. On occasion, the Company also generates revenues from cesium formate outside of a rental process and revenue is recognized upon delivery of the fluid.

Cabot maintains allowances for doubtful accounts based on an assessment of the collectibility of specific customer accounts, the aging of accounts receivable and other economic information on both an historical and prospective basis. Customer account balances are charged against the allowance when it is probable the receivable will not be recovered. Changes in the allowance during the first quarter of fiscal 2012 and 2011 were immaterial. There is no off-balance sheet credit exposure related to customer receivable balances.

Financial Instruments

Financial Instruments

Cabot's financial instruments consist primarily of cash and cash equivalents, accounts and notes receivable, investments, accounts payable and accrued liabilities, short-term and long-term debt, and derivative instruments. The carrying values of Cabot's financial instruments approximate fair value with the exception of long-term debt that has not been designated as part of a fair value hedge. The non-hedged long-term debt is recorded at amortized cost. The fair values of the Company's financial instruments are based on quoted market prices, if such prices are available. In situations where quoted market prices are not available, the Company relies on valuation models to derive fair value. Such valuation takes into account the ability of the financial counterparty to perform.

Cabot uses derivative financial instruments primarily for purposes of hedging exposures to fluctuations in interest rates and foreign currency exchange rates, which exist as part of its on-going business operations. Cabot does not enter into derivative contracts for speculative purposes, nor does it hold or issue any derivative contracts for trading purposes. All derivatives are recognized on the Consolidated Balance Sheets at fair value. Where Cabot has a legal right to offset derivative settlements under a master netting agreement with a counterparty, derivatives with that counterparty are presented on a net basis. The changes in the fair value of derivatives are recorded in either earnings or Accumulated other comprehensive income, depending on whether or not the instrument is designated as part of a hedge transaction and, if designated as part of a hedge transaction, the type of hedge transaction. The gains or losses on derivative instruments reported in Accumulated other comprehensive income are reclassified to earnings in the period in which earnings are affected by the underlying hedged item. The ineffective portion of all hedges is recognized in earnings during the period in which the ineffectiveness occurs.

In accordance with Cabot's risk management strategy, the Company may enter into certain derivative instruments that may not be designated as hedges for hedge accounting purposes. Although these derivatives are not designated as hedges, the Company believes that such instruments are closely correlated with the underlying exposure, thus managing the associated risk. The Company records in earnings the gains or losses from changes in the fair value of derivative instruments that are not designated as hedges. Cash movements associated with these instruments are presented in the Consolidated Statement of Cash Flows as Cash Flows from Operating Activities because the derivatives are designed to mitigate risk to the Company's cash flow from operations.

Income Tax In Interim Periods

Income Tax in Interim Periods

The Company records its tax provision or benefit on an interim basis using an estimated annual effective tax rate. This rate is applied to the current period ordinary income or loss to determine the income tax provision or benefit allocated to the interim period. Losses from jurisdictions for which no benefit can be recognized and the income tax effects of unusual or infrequent items are excluded from the estimated annual effective tax rate and are recognized in the impacted interim period as discrete items.

Valuation allowances are provided against the future tax benefits that arise from the losses in jurisdictions for which no benefit can be recognized. The estimated annual effective tax rate may be significantly impacted by nondeductible expenses and the Company's projected earnings mix by tax jurisdiction. Adjustments to the estimated annual effective income tax rate are recognized in the period when such estimates are revised.

Inventory Valuation

Inventory Valuation

The cost of most raw materials, work in process and finished goods inventories in the U.S. is determined by the last-in, first-out ("LIFO") method. Had the Company used the first-in, first-out ("FIFO") method instead of the LIFO method for such inventories, the value of those inventories would have been $53 million higher as of both December 31, 2011 and September 30, 2011. The cost of other U.S. and all non-U.S. inventories is determined using the average cost method or the FIFO method.

Cabot reviews inventory for both potential obsolescence and potential declines in anticipated selling prices. In this review, the Company makes assumptions about the future demand for and market value of the inventory, and based on these assumptions estimates the amount of any obsolete, unmarketable, slow moving or overvalued inventory. Cabot writes down the value of these inventories by an amount equal to the difference between the cost of the inventory and its estimated market value. There were no significant write-downs in either the three months ended December 31, 2011 or 2010.