Accounts Receivable and Notes Receivable and Credit Quality of Receivables - Components of Accounts and Notes Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current:
Receivables	$ 697	$ 791
Allowance for credit losses	(81)	(36)
Current receivables, net	616	755
Notes receivable	25	53
Financing Receivable, Allowance for Credit Loss, Noncurrent	(5)	0
Long-term:
Long-term receivables, net	20	53
Total accounts and notes receivable, net	$ 636	$ 808