Accounts Receivable - Schedule in Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	$ 20	$ 21
Total accounts receivable	2,365	2,540
Less: allowance for doubtful accounts	(106)	(142)
Accounts receivable, less allowance	2,259	2,398
Earned and unbilled receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	374	425
Trade and purchased receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 1,971	$ 2,094