Tax Matters - Reconciliation of Gross Unrecognized Tax Benefits - Footnotes (Details) - USD ($) $ in Millions	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020	[1]	Dec. 31, 2019
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 4,494	[1]	$ 6,068	[1]	$ 5,595		$ 5,381
Income Taxes Payable [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits	40		19
Other Current Tax Assets [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits	3		42
Noncurrent Deferred Tax Assets And Other Noncurrent Tax Assets [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits	1,200		3,000
Noncurrent Deferred Tax Liabilities [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits	5		5
Other Taxes Payable [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 3,200		$ 3,000

[1] In 2022, included in Income taxes payable ($40 million), Other current assets ($3 million), Noncurrent deferred tax assets and other noncurrent tax assets ($1.2 billion), Noncurrent deferred tax liabilities ($5 million) and Other taxes payable ($3.2 billion). In 2021, included in Income taxes payable ($19 million), Other current assets ($42 million), Noncurrent deferred tax assets and other noncurrent tax assets ($3.0 billion), Noncurrent deferred tax liabilities ($5 million) and Other taxes payable ($3.0 billion).