Accounts and Notes Receivable Allowance Rollforward (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Receivables [Abstract]
Accounts Receivable, Allowance for Credit Loss, Beginning Balance	$ 208	$ 174
Net provision for credit losses1	(7)	54	[1]
Write-offs charged against allowance / other1		(18)
Other deductions against allowance	9
Accounts Receivable, Allowance for Credit Loss, Ending Balance	$ 210	$ 210

[1] Prior year classifications in the changes in the allowance for doubtful receivables have been revised. Revisions did not impact the amount of the provision or the allowance for doubtful receivables recorded in the interim Consolidated Statements of Operations or the interim Consolidated Balance Sheets.