Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic earnings per share
Net income	$ 11,687	$ 9,443	$ 37,935	$ 16,995
Less: Preferred stock dividends	402	381	1,174	1,203
Net income applicable to common equity	11,285	9,062	36,761	15,792
Less: Dividends and undistributed earnings allocated to participating securities	56	47	185	80
Net income applicable to common stockholders	$ 11,229	$ 9,015	$ 36,576	$ 15,712
Total weighted-average basic shares outstanding (in shares)	2,999.9	3,077.8	3,036.4	3,083.3
Net income per share (in dollars per share)	$ 3.74	$ 2.93	$ 12.05	$ 5.10
Diluted earnings per share
Net income applicable to common stockholders	$ 11,229	$ 9,015	$ 36,576	$ 15,712
Total weighted-average basic shares outstanding (in shares)	2,999.9	3,077.8	3,036.4	3,083.3
Add: Dilutive impact of SARs and employee stock options, unvested PSUs and nondividend-earning RSUs (in shares)	5.2	5.0	5.3	4.8
Total weighted-average diluted shares outstanding (in shares)	3,005.1	3,082.8	3,041.7	3,088.1
Net income per share (in dollars per share)	$ 3.74	$ 2.92	$ 12.02	$ 5.09