Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic earnings per share
Net income	$ 29,131	$ 36,431	$ 32,474
Less: Preferred stock dividends	1,583	1,587	1,551
Net income applicable to common equity	27,548	34,844	30,923
Less: Dividends and undistributed earnings allocated to participating securities	138	202	214
Net income applicable to common stockholders	$ 27,410	$ 34,642	$ 30,709
Total weighted-average basic shares outstanding (in shares)	3,082.4	3,221.5	3,396.4
Net income per share (in dollars per share)	$ 8.89	$ 10.75	$ 9.04
Diluted earnings per share
Net income applicable to common stockholders	$ 27,410	$ 34,642	$ 30,709
Total weighted-average basic shares outstanding (in shares)	3,082.4	3,221.5	3,396.4
Add: Dilutive impact of SARs and employee stock options, unvested PSUs and non-dividend-earning RSUs, and warrants (in shares)	5.0	8.9	17.6
Total weighted-average diluted shares outstanding (in shares)	3,087.4	3,230.4	3,414.0
Net income per share (in dollars per share)	$ 8.88	$ 10.72	$ 9.00