Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Accounts Receivable Details [Abstract]
Allowance for doubtful accounts	$ 12		$ 12		$ 17
Allowance for doubtful accounts - receivables not expected to be collected in one year	47		47		51
Receivables Securitization Facility [Abstract]
Total capacity to transfer undivided interests to investors under the receivables securitization facility	800		$ 800
Receivables securitization facility maturity date			2022-07
Receivables securitization facility duration			3 years
Value of the outstanding undivided interest held by investors under the receivables securitization facility	0		$ 0		0
Accounts receivable supporting the undivided interest held by investors	1,300		1,300		$ 1,200
Cost of the receivables securitization facility - interest expense	$ 1	$ 2	$ 3	$ 6