Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic earnings per share
Net income	$ 9,080	$ 8,380	$ 27,911	$ 25,408
Less: Preferred stock dividends	423	379	1,201	1,167
Net income applicable to common equity	8,657	8,001	26,710	24,241
Less: Dividends and undistributed earnings allocated to participating securities	51	53	159	174
Net income applicable to common stockholders	$ 8,606	$ 7,948	$ 26,551	$ 24,067
Total weighted-average basic shares outstanding (in shares)	3,198.5	3,376.1	3,248.7	3,416.5
Net income per share (in dollars per share)	$ 2.69	$ 2.35	$ 8.17	$ 7.04
Diluted earnings per share
Net income applicable to common stockholders	$ 8,606	$ 7,948	$ 26,551	$ 24,067
Total weighted-average basic shares outstanding (in shares)	3,198.5	3,376.1	3,248.7	3,416.5
Add: Employee stock options, SARs, warrants and unvested PSUs (in shares)	8.7	18.2	9.3	19.7
Total weighted-average diluted shares outstanding (in shares)	3,207.2	3,394.3	3,258.0	3,436.2
Net income per share (in dollars per share)	$ 2.68	$ 2.34	$ 8.15	$ 7.00