Revenue Recognition Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts and other receivables	$ 992	$ 976
Accounts Receivable Related To Contracts With Customers [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts and other receivables	858	958
Other Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts and other receivables	$ 134	$ 18