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Consolidated Balance Sheets (Parentheticals) - USD ($)
$ in Millions
Sep. 30, 2020
Dec. 31, 2019
Allowance for doubtful accounts $ 139 $ 123
Accumulated depreciation $ 1,491 $ 1,338
Common stock par value $ 0.01 $ 0.01
Common Stock, Shares Authorized 1 1