Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Consolidated Balance Sheet
Allowances for doubtful accounts receivable	$ 233	$ 161
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)	577,749,638	575,184,835

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

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