Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Income from continuing operations, net of tax	$ 2,403	$ 3,327
Income (loss) from discontinued operations, net of tax	0	(2)
Net income	2,403	3,325
Dividends and undistributed earnings allocated to participating securities	(28)	(28)
Preferred stock dividends	(57)	(61)
Net income available to common stockholders	$ 2,318	$ 3,236
Total weighted-average basic common shares outstanding	410.4	458.6
Effect of dilutive securities:
Stock options	0.5	0.8
Other contingently issuable shares	1.3	0.7
Total effect of dilutive securities	1.8	1.5
Weighted Average Number of Shares Outstanding, Diluted, Total	412.2	460.1
Basic earnings per common share:
Net income from continuing operations	$ 5.65	$ 7.06
Net income per basic common share	5.65	7.06
Diluted earnings per common share:
Net income from continuing operations	5.62	7.03
Net income per diluted common share	$ 5.62	$ 7.03