Income Taxes - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Indirect tax effects excluded	$ 63
Alternative minimum tax credit carryforward	23
Foreign tax credits	331	$ 340
Valuation allowance	129	210	$ 273
Unrecognized tax benefits that would impact effective tax rate	367	$ 315
Federal
Income Tax Contingency [Line Items]
Unrecognized tax benefits, net operating loss	470
Operating loss carryforwards	138
Federal | Research Tax Credit Carryforward
Income Tax Contingency [Line Items]
Foreign tax credits	347
State
Income Tax Contingency [Line Items]
Unrecognized tax benefits, net operating loss	710
Operating loss carryforwards	$ 282