Accounts and Notes Receivable Allowance Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Receivables [Abstract]
Accounts Receivable, Allowance for Credit Loss, Beginning Balance	$ 208	$ 174
Net provision for credit losses	(5)	60
Write-offs charged against allowance		(1)
Recoveries collected		(30)
Accounts Receivable, Allowance for Credit Loss, Ending Balance	$ 203	$ 203