Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Allowance for bad debt	$ 137	$ 117
Accumulated depreciation	$ 11,007	$ 9,480
Shareholders’ equity:
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	2,000us-gaap_CommonStockSharesAuthorized	2,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	1,071us-gaap_CommonStockSharesIssued	1,072us-gaap_CommonStockSharesIssued
Treasury shares (in shares)	223us-gaap_TreasuryStockShares	223us-gaap_TreasuryStockShares

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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