Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 24,449	$ 21,006	$ 22,984	$ 23,071
Net change in accumulated other comprehensive income (loss)	17	85	14	(174)
Ending Balance	25,539	21,062	25,539	21,062
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Total tax impact	(39)	(115)	(23)	175
Decrease due to amounts reclassified into earnings
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net change in accumulated other comprehensive income (loss)	0	(3)	0	(3)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2,898)	(2,996)	(2,895)	(2,737)
Ending Balance	(2,881)	(2,911)	(2,881)	(2,911)
Net Unrealized Gains (Losses) on Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	53	90	65	33
Net change in accumulated other comprehensive income (loss)	(11)	(5)	(23)	52
Ending Balance	42	85	42	85
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Total tax impact	(3)	(2)	(6)	16
Foreign Currency Translation Adjustment Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2,246)	(2,511)	(2,229)	(2,189)
Net change in accumulated other comprehensive income (loss)	19	123	2	(199)
Ending Balance	(2,227)	(2,388)	(2,227)	(2,388)
Net Unrealized Pension and Other Postretirement Benefit Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(705)	(575)	(731)	(581)
Net change in accumulated other comprehensive income (loss)	9	(33)	35	(27)
Ending Balance	(696)	(608)	(696)	(608)
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Total tax impact	2	(1)	13	11
Net translation on investments in foreign operations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net change in accumulated other comprehensive income (loss)	127	465	104	(589)
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Total tax impact	(3)	(6)	5	24
Net hedges of investments in foreign operations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net change in accumulated other comprehensive income (loss)	(108)	(339)	(102)	393
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Total tax impact	$ (35)	$ (106)	$ (35)	$ 124