Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Decrease in income tax expense	$ 4,583
Effective tax rate	25.40%	48.60%	27.80%
Decrease in deferred tax liabilities	$ 403
Increase in deferred tax assets	3,621
Loss carry forward	19,763
Tax credit carryforward	1,056
Carry forward amount of foreign tax credit with expiration dates	10,585
Existing undistributed accumulated earnings of foreign subsidiary	$ 52,100
Percentage of impact of unrecognized tax benefits on effective tax rate if subsequently recognized	83.00%
Unrecognized tax benefits	$ 5,018	$ 4,987	$ 5,070	$ 4,828
Anticipated interest and penalty obligations	(95)
Accrued charges		30
Income tax benefit expense associated with interest and penalties	$ (124)	$ (3)	$ 8