Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Consolidated Balance Sheet
Allowances for doubtful accounts receivable	$ 231	$ 233
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares issued (in shares)	944,033,056	944,033,056
Common stock, Shares outstanding (in shares)	579,675,002	577,749,638
Treasury stock (in shares)	364,358,054	366,283,418

Amount of allowance for credit loss on accounts receivable, classified as current.

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