Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Receivables, allowance for doubtful accounts	$ 137	$ 118
Preferred stock, par	$ 1	$ 1
Preferred stock, shares authorized	10,000,000us-gaap_PreferredStockSharesAuthorized	10,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par	$ 0.1667	$ 0.1667
Common stock, shares authorized	300,000,000us-gaap_CommonStockSharesAuthorized	300,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	197,951,551us-gaap_CommonStockSharesIssued	196,275,506us-gaap_CommonStockSharesIssued
Treasury stock, shares	48,347,541us-gaap_TreasuryStockShares	42,245,097us-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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