Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 106	$ 114
Common stock, par value per share	$ 0.50	$ 0.50
Common stock, shares authorized	1,200,000,000us-gaap_CommonStockSharesAuthorized	1,200,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	953,354,012us-gaap_CommonStockSharesIssued	953,354,012us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	688,677,106us-gaap_CommonStockSharesOutstanding	696,605,222us-gaap_CommonStockSharesOutstanding
Treasury stock, shares	264,676,906us-gaap_TreasuryStockShares	256,748,790us-gaap_TreasuryStockShares

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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