Income Taxes, Liability for Unrecognized Tax Benefits Presented in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Amounts Recognized in Balance Sheets for Uncertain Tax Positions
Other long-term liabilities and Deferred tax liabilities	$ 859	$ 954
Liability for unrecognized tax benefits presented in our balance sheets	931	968
Income Taxes Payable [Member]
Amounts Recognized in Balance Sheets for Uncertain Tax Positions
Income taxes payable	59	0
Other Long-term Liabilities [Member]
Amounts Recognized in Balance Sheets for Uncertain Tax Positions
Other long-term liabilities and Deferred tax liabilities	859	954
Deferred Tax Liabilities[Member]
Amounts Recognized in Balance Sheets for Uncertain Tax Positions
Other long-term liabilities and Deferred tax liabilities	$ 13	$ 14